Merge branch 'master' into testing

12 files changed, 565 insertions, 918 deletions

diff --git a/ext/fg/js/api.js b/ext/fg/js/api.js
deleted file mode 100644
index 0e100b59..00000000
--- a/ext/fg/js/api.js
+++ /dev/null
@@ -1,118 +0,0 @@
-/*
- * Copyright (C) 2016-2017  Alex Yatskov <alex@foosoft.net>
- * Author: Alex Yatskov <alex@foosoft.net>
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-
-function apiOptionsGet(optionsContext) {
-    return _apiInvoke('optionsGet', {optionsContext});
-}
-
-function apiOptionsSet(changedOptions, optionsContext, source) {
-    return _apiInvoke('optionsSet', {changedOptions, optionsContext, source});
-}
-
-function apiTermsFind(text, details, optionsContext) {
-    return _apiInvoke('termsFind', {text, details, optionsContext});
-}
-
-function apiTextParse(text, optionsContext) {
-    return _apiInvoke('textParse', {text, optionsContext});
-}
-
-function apiTextParseMecab(text, optionsContext) {
-    return _apiInvoke('textParseMecab', {text, optionsContext});
-}
-
-function apiKanjiFind(text, optionsContext) {
-    return _apiInvoke('kanjiFind', {text, optionsContext});
-}
-
-function apiDefinitionAdd(definition, mode, context, optionsContext) {
-    return _apiInvoke('definitionAdd', {definition, mode, context, optionsContext});
-}
-
-function apiDefinitionsAddable(definitions, modes, optionsContext) {
-    return _apiInvoke('definitionsAddable', {definitions, modes, optionsContext}).catch(() => null);
-}
-
-function apiNoteView(noteId) {
-    return _apiInvoke('noteView', {noteId});
-}
-
-function apiTemplateRender(template, data, dynamic) {
-    return _apiInvoke('templateRender', {data, template, dynamic});
-}
-
-function apiAudioGetUrl(definition, source, optionsContext) {
-    return _apiInvoke('audioGetUrl', {definition, source, optionsContext});
-}
-
-function apiCommandExec(command, params) {
-    return _apiInvoke('commandExec', {command, params});
-}
-
-function apiScreenshotGet(options) {
-    return _apiInvoke('screenshotGet', {options});
-}
-
-function apiForward(action, params) {
-    return _apiInvoke('forward', {action, params});
-}
-
-function apiFrameInformationGet() {
-    return _apiInvoke('frameInformationGet');
-}
-
-function apiInjectStylesheet(css) {
-    return _apiInvoke('injectStylesheet', {css});
-}
-
-function apiGetEnvironmentInfo() {
-    return _apiInvoke('getEnvironmentInfo');
-}
-
-function apiClipboardGet() {
-    return _apiInvoke('clipboardGet');
-}
-
-function _apiInvoke(action, params={}) {
-    const data = {action, params};
-    return new Promise((resolve, reject) => {
-        try {
-            chrome.runtime.sendMessage(data, (response) => {
-                _apiCheckLastError(chrome.runtime.lastError);
-                if (response !== null && typeof response === 'object') {
-                    if (typeof response.error !== 'undefined') {
-                        reject(jsonToError(response.error));
-                    } else {
-                        resolve(response.result);
-                    }
-                } else {
-                    const message = response === null ? 'Unexpected null response' : `Unexpected response of type ${typeof response}`;
-                    reject(new Error(`${message} (${JSON.stringify(data)})`));
-                }
-            });
-        } catch (e) {
-            window.yomichan_orphaned = true;
-            reject(e);
-        }
-    });
-}
-
-function _apiCheckLastError() {
-    // NOP
-}
diff --git a/ext/fg/js/document.js b/ext/fg/js/document.js
index 10dea7df..e068e3ba 100644
--- a/ext/fg/js/document.js
+++ b/ext/fg/js/document.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2017  Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2016-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,7 +13,7 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
@@ -97,15 +97,16 @@ function docImposterCreate(element, isTextarea) {
 
 function docElementsFromPoint(x, y, all) {
     if (all) {
-        return document.elementsFromPoint(x, y);
+        // document.elementsFromPoint can return duplicates which must be removed.
+        const elements = document.elementsFromPoint(x, y);
+        return elements.filter((e, i) => elements.indexOf(e) === i);
     }
 
     const e = document.elementFromPoint(x, y);
     return e !== null ? [e] : [];
 }
 
-function docRangeFromPoint(x, y, options) {
-    const deepDomScan = options.scanning.deepDomScan;
+function docRangeFromPoint(x, y, deepDomScan) {
     const elements = docElementsFromPoint(x, y, deepDomScan);
     let imposter = null;
     let imposterContainer = null;
@@ -319,7 +320,7 @@ function disableTransparentElement(elements, i, modifications) {
         if (isElementTransparent(element)) {
             const style = element.hasAttribute('style') ? element.getAttribute('style') : null;
             modifications.push({element, style});
-            element.style.pointerEvents = 'none';
+            element.style.setProperty('pointer-events', 'none', 'important');
             return i;
         }
     }
diff --git a/ext/fg/js/float.js b/ext/fg/js/float.js
index ae54be00..513d246b 100644
--- a/ext/fg/js/float.js
+++ b/ext/fg/js/float.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2017  Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2016-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,7 +13,7 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
@@ -27,17 +27,24 @@ class DisplayFloat extends Display {
             url: window.location.href
         };
 
+        this._orphaned = false;
+
+        yomichan.on('orphaned', () => this.onOrphaned());
         window.addEventListener('message', (e) => this.onMessage(e), false);
     }
 
     onError(error) {
-        if (window.yomichan_orphaned) {
+        if (this._orphaned) {
             this.setContentOrphaned();
         } else {
             logError(error, true);
         }
     }
 
+    onOrphaned() {
+        this._orphaned = true;
+    }
+
     onSearchClear() {
         window.parent.postMessage('popupClose', '*');
     }
@@ -48,24 +55,22 @@ class DisplayFloat extends Display {
 
     onMessage(e) {
         const {action, params} = e.data;
-        const handlers = DisplayFloat.messageHandlers;
-        if (hasOwn(handlers, action)) {
-            const handler = handlers[action];
-            handler(this, params);
-        }
+        const handler = DisplayFloat._messageHandlers.get(action);
+        if (typeof handler !== 'function') { return; }
+
+        handler(this, params);
     }
 
     onKeyDown(e) {
         const key = Display.getKeyFromEvent(e);
-        const handlers = DisplayFloat.onKeyDownHandlers;
-        if (hasOwn(handlers, key)) {
-            const handler = handlers[key];
+        const handler = DisplayFloat._onKeyDownHandlers.get(key);
+        if (typeof handler === 'function') {
             if (handler(this, e)) {
                 e.preventDefault();
-                return;
+                return true;
             }
         }
-        super.onKeyDown(e);
+        return super.onKeyDown(e);
     }
 
     getOptionsContext() {
@@ -97,21 +102,21 @@ class DisplayFloat extends Display {
     }
 }
 
-DisplayFloat.onKeyDownHandlers = {
-    'C': (self, e) => {
+DisplayFloat._onKeyDownHandlers = new Map([
+    ['C', (self, e) => {
         if (e.ctrlKey && !window.getSelection().toString()) {
             self.onSelectionCopy();
             return true;
         }
         return false;
-    }
-};
+    }]
+]);
 
-DisplayFloat.messageHandlers = {
-    setContent: (self, {type, details}) => self.setContent(type, details),
-    clearAutoPlayTimer: (self) => self.clearAutoPlayTimer(),
-    setCustomCss: (self, {css}) => self.setCustomCss(css),
-    initialize: (self, {options, popupInfo, url, childrenSupported}) => self.initialize(options, popupInfo, url, childrenSupported)
-};
+DisplayFloat._messageHandlers = new Map([
+    ['setContent', (self, {type, details}) => self.setContent(type, details)],
+    ['clearAutoPlayTimer', (self) => self.clearAutoPlayTimer()],
+    ['setCustomCss', (self, {css}) => self.setCustomCss(css)],
+    ['initialize', (self, {options, popupInfo, url, childrenSupported}) => self.initialize(options, popupInfo, url, childrenSupported)]
+]);
 
-window.yomichan_display = new DisplayFloat();
+DisplayFloat.instance = new DisplayFloat();
diff --git a/ext/fg/js/frontend-api-receiver.js b/ext/fg/js/frontend-api-receiver.js
index 7d38ddd5..642d96df 100644
--- a/ext/fg/js/frontend-api-receiver.js
+++ b/ext/fg/js/frontend-api-receiver.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2019-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,14 +13,14 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
 class FrontendApiReceiver {
-    constructor(source='', handlers={}) {
-        this.source = source;
-        this.handlers = handlers;
+    constructor(source='', handlers=new Map()) {
+        this._source = source;
+        this._handlers = handlers;
 
         chrome.runtime.onConnect.addListener(this.onConnect.bind(this));
     }
@@ -32,16 +32,13 @@ class FrontendApiReceiver {
     }
 
     onMessage(port, {id, action, params, target, senderId}) {
-        if (
-            target !== this.source ||
-            !hasOwn(this.handlers, action)
-        ) {
-            return;
-        }
+        if (target !== this._source) { return; }
+
+        const handler = this._handlers.get(action);
+        if (typeof handler !== 'function') { return; }
 
         this.sendAck(port, id, senderId);
 
-        const handler = this.handlers[action];
         handler(params).then(
             (result) => {
                 this.sendResult(port, id, senderId, {result});
diff --git a/ext/fg/js/frontend-api-sender.js b/ext/fg/js/frontend-api-sender.js
index af998a8f..93c2e593 100644
--- a/ext/fg/js/frontend-api-sender.js
+++ b/ext/fg/js/frontend-api-sender.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2019-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,7 +13,7 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
@@ -22,7 +22,7 @@ class FrontendApiSender {
         this.senderId = FrontendApiSender.generateId(16);
         this.ackTimeout = 3000; // 3 seconds
         this.responseTimeout = 10000; // 10 seconds
-        this.callbacks = {};
+        this.callbacks = new Map();
         this.disconnected = false;
         this.nextId = 0;
 
@@ -43,7 +43,7 @@ class FrontendApiSender {
 
         return new Promise((resolve, reject) => {
             const info = {id, resolve, reject, ack: false, timer: null};
-            this.callbacks[id] = info;
+            this.callbacks.set(id, info);
             info.timer = setTimeout(() => this.onError(id, 'Timeout (ack)'), this.ackTimeout);
 
             this.port.postMessage({id, action, params, target, senderId: this.senderId});
@@ -71,19 +71,18 @@ class FrontendApiSender {
     onDisconnect() {
         this.disconnected = true;
 
-        const ids = Object.keys(this.callbacks);
-        for (const id of ids) {
+        for (const id of this.callbacks.keys()) {
             this.onError(id, 'Disconnected');
         }
     }
 
     onAck(id) {
-        if (!hasOwn(this.callbacks, id)) {
+        const info = this.callbacks.get(id);
+        if (typeof info === 'undefined') {
             console.warn(`ID ${id} not found for ack`);
             return;
         }
 
-        const info = this.callbacks[id];
         if (info.ack) {
             console.warn(`Request ${id} already ack'd`);
             return;
@@ -95,18 +94,18 @@ class FrontendApiSender {
     }
 
     onResult(id, data) {
-        if (!hasOwn(this.callbacks, id)) {
+        const info = this.callbacks.get(id);
+        if (typeof info === 'undefined') {
             console.warn(`ID ${id} not found`);
             return;
         }
 
-        const info = this.callbacks[id];
         if (!info.ack) {
             console.warn(`Request ${id} not ack'd`);
             return;
         }
 
-        delete this.callbacks[id];
+        this.callbacks.delete(id);
         clearTimeout(info.timer);
         info.timer = null;
 
@@ -118,9 +117,9 @@ class FrontendApiSender {
     }
 
     onError(id, reason) {
-        if (!hasOwn(this.callbacks, id)) { return; }
-        const info = this.callbacks[id];
-        delete this.callbacks[id];
+        const info = this.callbacks.get(id);
+        if (typeof info === 'undefined') { return; }
+        this.callbacks.delete(id);
         info.timer = null;
         info.reject(new Error(reason));
     }
diff --git a/ext/fg/js/frontend-initialize.js b/ext/fg/js/frontend-initialize.js
index 37a82faa..9c923fea 100644
--- a/ext/fg/js/frontend-initialize.js
+++ b/ext/fg/js/frontend-initialize.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019  Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2019-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,8 +13,23 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
-window.yomichan_frontend = Frontend.create();
+async function main() {
+    const data = window.frontendInitializationData || {};
+    const {id, depth=0, parentFrameId, ignoreNodes, url, proxy=false} = data;
+
+    let popupHost = null;
+    if (!proxy) {
+        popupHost = new PopupProxyHost();
+        await popupHost.prepare();
+    }
+
+    const popup = proxy ? new PopupProxy(depth + 1, id, parentFrameId, url) : popupHost.createPopup(null, depth);
+    const frontend = new Frontend(popup, ignoreNodes);
+    await frontend.prepare();
+}
+
+main();
diff --git a/ext/fg/js/frontend.js b/ext/fg/js/frontend.js
index 9a1d507b..034d9075 100644
--- a/ext/fg/js/frontend.js
+++ b/ext/fg/js/frontend.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2017  Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2016-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,221 +13,47 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
-class Frontend {
+class Frontend extends TextScanner {
     constructor(popup, ignoreNodes) {
+        super(
+            window,
+            ignoreNodes,
+            popup.isProxy() ? [] : [popup.getContainer()],
+            [(x, y) => this.popup.containsPoint(x, y)]
+        );
+
         this.popup = popup;
-        this.popupTimerPromise = null;
-        this.textSourceCurrent = null;
-        this.pendingLookup = false;
         this.options = null;
-        this.ignoreNodes = (Array.isArray(ignoreNodes) && ignoreNodes.length > 0 ? ignoreNodes.join(',') : null);
 
         this.optionsContext = {
             depth: popup.depth,
             url: popup.url
         };
 
-        this.primaryTouchIdentifier = null;
-        this.preventNextContextMenu = false;
-        this.preventNextMouseDown = false;
-        this.preventNextClick = false;
-        this.preventScroll = false;
-
-        this.enabled = false;
-        this.eventListeners = [];
-
-        this.isPreparedPromiseResolve = null;
-        this.isPreparedPromise = new Promise((resolve) => { this.isPreparedPromiseResolve = resolve; });
-
-        this.lastShowPromise = Promise.resolve();
-    }
-
-    static create() {
-        const data = window.frontendInitializationData || {};
-        const {id, depth=0, parentFrameId, ignoreNodes, url, proxy=false} = data;
-
-        const popup = proxy ? new PopupProxy(depth + 1, id, parentFrameId, url) : PopupProxyHost.instance.createPopup(null, depth);
-        const frontend = new Frontend(popup, ignoreNodes);
-        frontend.prepare();
-        return frontend;
+        this._orphaned = true;
+        this._lastShowPromise = Promise.resolve();
     }
 
     async prepare() {
         try {
             await this.updateOptions();
 
+            yomichan.on('orphaned', () => this.onOrphaned());
+            yomichan.on('optionsUpdate', () => this.updateOptions());
             chrome.runtime.onMessage.addListener(this.onRuntimeMessage.bind(this));
-            this.isPreparedPromiseResolve();
         } catch (e) {
             this.onError(e);
         }
     }
 
-    isPrepared() {
-        return this.isPreparedPromise;
-    }
-
-    onMouseOver(e) {
-        if (e.target === this.popup.container) {
-            this.popupTimerClear();
-        }
-    }
-
-    onMouseMove(e) {
-        this.popupTimerClear();
-
-        if (this.pendingLookup || DOM.isMouseButtonDown(e, 'primary')) {
-            return;
-        }
-
-        const scanningOptions = this.options.scanning;
-        const scanningModifier = scanningOptions.modifier;
-        if (!(
-            Frontend.isScanningModifierPressed(scanningModifier, e) ||
-            (scanningOptions.middleMouse && DOM.isMouseButtonDown(e, 'auxiliary'))
-        )) {
-            return;
-        }
-
-        const search = async () => {
-            if (scanningModifier === 'none') {
-                if (!await this.popupTimerWait()) {
-                    // Aborted
-                    return;
-                }
-            }
-
-            await this.searchAt(e.clientX, e.clientY, 'mouse');
-        };
-
-        search();
-    }
-
-    onMouseDown(e) {
-        if (this.preventNextMouseDown) {
-            this.preventNextMouseDown = false;
-            this.preventNextClick = true;
-            e.preventDefault();
-            e.stopPropagation();
-            return false;
-        }
-
-        if (e.button === 0) {
-            this.popupTimerClear();
-            this.searchClear(true);
-        }
-    }
-
-    onMouseOut() {
-        this.popupTimerClear();
-    }
-
-    onClick(e) {
-        if (this.preventNextClick) {
-            this.preventNextClick = false;
-            e.preventDefault();
-            e.stopPropagation();
-            return false;
-        }
-    }
-
-    onAuxClick() {
-        this.preventNextContextMenu = false;
-    }
-
-    onContextMenu(e) {
-        if (this.preventNextContextMenu) {
-            this.preventNextContextMenu = false;
-            e.preventDefault();
-            e.stopPropagation();
-            return false;
-        }
-    }
-
-    onTouchStart(e) {
-        if (this.primaryTouchIdentifier !== null || e.changedTouches.length === 0) {
-            return;
-        }
-
-        this.preventScroll = false;
-        this.preventNextContextMenu = false;
-        this.preventNextMouseDown = false;
-        this.preventNextClick = false;
-
-        const primaryTouch = e.changedTouches[0];
-        if (DOM.isPointInSelection(primaryTouch.clientX, primaryTouch.clientY, window.getSelection())) {
-            return;
-        }
-
-        this.primaryTouchIdentifier = primaryTouch.identifier;
-
-        if (this.pendingLookup) {
-            return;
-        }
-
-        const textSourceCurrentPrevious = this.textSourceCurrent !== null ? this.textSourceCurrent.clone() : null;
-
-        this.searchAt(primaryTouch.clientX, primaryTouch.clientY, 'touchStart')
-        .then(() => {
-            if (
-                this.textSourceCurrent === null ||
-                this.textSourceCurrent.equals(textSourceCurrentPrevious)
-            ) {
-                return;
-            }
-
-            this.preventScroll = true;
-            this.preventNextContextMenu = true;
-            this.preventNextMouseDown = true;
-        });
-    }
-
-    onTouchEnd(e) {
-        if (
-            this.primaryTouchIdentifier === null ||
-            this.getIndexOfTouch(e.changedTouches, this.primaryTouchIdentifier) < 0
-        ) {
-            return;
-        }
-
-        this.primaryTouchIdentifier = null;
-        this.preventScroll = false;
-        this.preventNextClick = false;
-        // Don't revert context menu and mouse down prevention,
-        // since these events can occur after the touch has ended.
-        // this.preventNextContextMenu = false;
-        // this.preventNextMouseDown = false;
-    }
-
-    onTouchCancel(e) {
-        this.onTouchEnd(e);
-    }
-
-    onTouchMove(e) {
-        if (!this.preventScroll || !e.cancelable || this.primaryTouchIdentifier === null) {
-            return;
-        }
-
-        const touches = e.changedTouches;
-        const index = this.getIndexOfTouch(touches, this.primaryTouchIdentifier);
-        if (index < 0) {
-            return;
-        }
-
-        const primaryTouch = touches[index];
-        this.searchAt(primaryTouch.clientX, primaryTouch.clientY, 'touchMove');
-
-        e.preventDefault(); // Disable scroll
-    }
-
     async onResize() {
-        if (this.textSourceCurrent !== null && await this.popup.isVisibleAsync()) {
-            const textSource = this.textSourceCurrent;
-            this.lastShowPromise = this.popup.showContent(
+        const textSource = this.textSourceCurrent;
+        if (textSource !== null && await this.popup.isVisible()) {
+            this._lastShowPromise = this.popup.showContent(
                 textSource.getRect(),
                 textSource.getWritingMode()
             );
@@ -236,128 +62,43 @@ class Frontend {
 
     onWindowMessage(e) {
         const action = e.data;
-        const handlers = Frontend.windowMessageHandlers;
-        if (hasOwn(handlers, action)) {
-            const handler = handlers[action];
-            handler(this);
-        }
-    }
-
-    onRuntimeMessage({action, params}, sender, callback) {
-        const handlers = Frontend.runtimeMessageHandlers;
-        if (hasOwn(handlers, action)) {
-            const handler = handlers[action];
-            const result = handler(this, params);
-            callback(result);
-        }
-    }
+        const handler = Frontend._windowMessageHandlers.get(action);
+        if (typeof handler !== 'function') { return false; }
 
-    onError(error) {
-        logError(error, false);
+        handler(this);
     }
 
-    setEnabled(enabled) {
-        if (enabled) {
-            if (!this.enabled) {
-                this.hookEvents();
-                this.enabled = true;
-            }
-        } else {
-            if (this.enabled) {
-                this.clearEventListeners();
-                this.enabled = false;
-            }
-            this.searchClear(false);
-        }
-    }
+    onRuntimeMessage({action, params}, sender, callback) {
+        const handler = Frontend._runtimeMessageHandlers.get(action);
+        if (typeof handler !== 'function') { return false; }
 
-    hookEvents() {
-        this.addEventListener(window, 'message', this.onWindowMessage.bind(this));
-        this.addEventListener(window, 'mousedown', this.onMouseDown.bind(this));
-        this.addEventListener(window, 'mousemove', this.onMouseMove.bind(this));
-        this.addEventListener(window, 'mouseover', this.onMouseOver.bind(this));
-        this.addEventListener(window, 'mouseout', this.onMouseOut.bind(this));
-        this.addEventListener(window, 'resize', this.onResize.bind(this));
-
-        if (this.options.scanning.touchInputEnabled) {
-            this.addEventListener(window, 'click', this.onClick.bind(this));
-            this.addEventListener(window, 'auxclick', this.onAuxClick.bind(this));
-            this.addEventListener(window, 'touchstart', this.onTouchStart.bind(this));
-            this.addEventListener(window, 'touchend', this.onTouchEnd.bind(this));
-            this.addEventListener(window, 'touchcancel', this.onTouchCancel.bind(this));
-            this.addEventListener(window, 'touchmove', this.onTouchMove.bind(this), {passive: false});
-            this.addEventListener(window, 'contextmenu', this.onContextMenu.bind(this));
-        }
+        const result = handler(this, params, sender);
+        callback(result);
+        return false;
     }
 
-    addEventListener(node, type, listener, options) {
-        node.addEventListener(type, listener, options);
-        this.eventListeners.push([node, type, listener, options]);
+    onOrphaned() {
+        this._orphaned = true;
     }
 
-    clearEventListeners() {
-        for (const [node, type, listener, options] of this.eventListeners) {
-            node.removeEventListener(type, listener, options);
-        }
-        this.eventListeners = [];
+    getMouseEventListeners() {
+        return [
+            ...super.getMouseEventListeners(),
+            [window, 'message', this.onWindowMessage.bind(this)],
+            [window, 'resize', this.onResize.bind(this)]
+        ];
     }
 
     async updateOptions() {
         this.options = await apiOptionsGet(this.getOptionsContext());
-        this.setEnabled(this.options.general.enable);
         await this.popup.setOptions(this.options);
+        this.setEnabled(this.options.general.enable);
     }
 
-    async popupTimerWait() {
-        const delay = this.options.scanning.delay;
-        const promise = promiseTimeout(delay, true);
-        this.popupTimerPromise = promise;
-        try {
-            return await promise;
-        } finally {
-            if (this.popupTimerPromise === promise) {
-                this.popupTimerPromise = null;
-            }
-        }
-    }
-
-    popupTimerClear() {
-        if (this.popupTimerPromise !== null) {
-            this.popupTimerPromise.resolve(false);
-            this.popupTimerPromise = null;
-        }
-    }
-
-    async searchAt(x, y, cause) {
-        try {
-            this.popupTimerClear();
-
-            if (this.pendingLookup || await this.popup.containsPoint(x, y)) {
-                return;
-            }
-
-            const textSource = docRangeFromPoint(x, y, this.options);
-            if (this.textSourceCurrent !== null && this.textSourceCurrent.equals(textSource)) {
-                return;
-            }
-
-            try {
-                await this.searchSource(textSource, cause);
-            } finally {
-                if (textSource !== null) {
-                    textSource.cleanup();
-                }
-            }
-        } catch (e) {
-            this.onError(e);
-        }
-    }
-
-    async searchSource(textSource, cause) {
+    async onSearchSource(textSource, cause) {
         let results = null;
 
         try {
-            this.pendingLookup = true;
             if (textSource !== null) {
                 results = (
                     await this.findTerms(textSource) ||
@@ -369,9 +110,9 @@ class Frontend {
                 }
             }
         } catch (e) {
-            if (window.yomichan_orphaned) {
+            if (this._orphaned) {
                 if (textSource !== null && this.options.scanning.modifier !== 'none') {
-                    this.lastShowPromise = this.popup.showContent(
+                    this._lastShowPromise = this.popup.showContent(
                         textSource.getRect(),
                         textSource.getWritingMode(),
                         'orphaned'
@@ -382,10 +123,8 @@ class Frontend {
             }
         } finally {
             if (results === null && this.options.scanning.autoHideResults) {
-                this.searchClear(true);
+                this.onSearchClear(true);
             }
-
-            this.pendingLookup = false;
         }
 
         return results;
@@ -394,17 +133,16 @@ class Frontend {
     showContent(textSource, focus, definitions, type) {
         const sentence = docSentenceExtract(textSource, this.options.anki.sentenceExt);
         const url = window.location.href;
-        this.lastShowPromise = this.popup.showContent(
+        this._lastShowPromise = this.popup.showContent(
             textSource.getRect(),
             textSource.getWritingMode(),
             type,
             {definitions, context: {sentence, url, focus, disableHistory: true}}
         );
+    }
 
-        this.textSourceCurrent = textSource;
-        if (this.options.scanning.selectText) {
-            textSource.select();
-        }
+    showContentCompleted() {
+        return this._lastShowPromise;
     }
 
     async findTerms(textSource) {
@@ -433,82 +171,23 @@ class Frontend {
         return {definitions, type: 'kanji'};
     }
 
-    searchClear(changeFocus) {
+    onSearchClear(changeFocus) {
         this.popup.hide(changeFocus);
         this.popup.clearAutoPlayTimer();
-
-        if (this.textSourceCurrent !== null) {
-            if (this.options.scanning.selectText) {
-                this.textSourceCurrent.deselect();
-            }
-
-            this.textSourceCurrent = null;
-        }
-    }
-
-    getIndexOfTouch(touchList, identifier) {
-        for (const i in touchList) {
-            const t = touchList[i];
-            if (t.identifier === identifier) {
-                return i;
-            }
-        }
-        return -1;
-    }
-
-    setTextSourceScanLength(textSource, length) {
-        textSource.setEndOffset(length);
-        if (this.ignoreNodes === null || !textSource.range) {
-            return;
-        }
-
-        length = textSource.text().length;
-        while (textSource.range && length > 0) {
-            const nodes = TextSourceRange.getNodesInRange(textSource.range);
-            if (!TextSourceRange.anyNodeMatchesSelector(nodes, this.ignoreNodes)) {
-                break;
-            }
-            --length;
-            textSource.setEndOffset(length);
-        }
+        super.onSearchClear(changeFocus);
     }
 
     getOptionsContext() {
         this.optionsContext.url = this.popup.url;
         return this.optionsContext;
     }
-
-    static isScanningModifierPressed(scanningModifier, mouseEvent) {
-        switch (scanningModifier) {
-            case 'alt': return mouseEvent.altKey;
-            case 'ctrl': return mouseEvent.ctrlKey;
-            case 'shift': return mouseEvent.shiftKey;
-            case 'none': return true;
-            default: return false;
-        }
-    }
 }
 
-Frontend.windowMessageHandlers = {
-    popupClose: (self) => {
-        self.searchClear(true);
-    },
-
-    selectionCopy: () => {
-        document.execCommand('copy');
-    }
-};
-
-Frontend.runtimeMessageHandlers = {
-    optionsUpdate: (self) => {
-        self.updateOptions();
-    },
+Frontend._windowMessageHandlers = new Map([
+    ['popupClose', (self) => self.onSearchClear(true)],
+    ['selectionCopy', () => document.execCommand('copy')]
+]);
 
-    popupSetVisibleOverride: (self, {visible}) => {
-        self.popup.setVisibleOverride(visible);
-    },
-
-    getUrl: () => {
-        return {url: window.location.href};
-    }
-};
+Frontend._runtimeMessageHandlers = new Map([
+    ['popupSetVisibleOverride', (self, {visible}) => { self.popup.setVisibleOverride(visible); }]
+]);
diff --git a/ext/fg/js/popup-nested.js b/ext/fg/js/popup-nested.js
index 31cb1cda..bacf3b93 100644
--- a/ext/fg/js/popup-nested.js
+++ b/ext/fg/js/popup-nested.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2019-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,7 +13,7 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
@@ -41,6 +41,7 @@ async function popupNestedInitialize(id, depth, parentFrameId, url) {
     window.frontendInitializationData = {id, depth, parentFrameId, ignoreNodes, url, proxy: true};
 
     const scriptSrcs = [
+        '/mixed/js/text-scanner.js',
         '/fg/js/frontend-api-sender.js',
         '/fg/js/popup.js',
         '/fg/js/popup-proxy.js',
diff --git a/ext/fg/js/popup-proxy-host.js b/ext/fg/js/popup-proxy-host.js
index b2f18b97..c4f0c6ff 100644
--- a/ext/fg/js/popup-proxy-host.js
+++ b/ext/fg/js/popup-proxy-host.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2019-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,126 +13,127 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
 class PopupProxyHost {
     constructor() {
-        this.popups = {};
-        this.nextId = 0;
-        this.apiReceiver = null;
-        this.frameIdPromise = null;
+        this._popups = new Map();
+        this._nextId = 0;
+        this._apiReceiver = null;
+        this._frameIdPromise = null;
     }
 
-    static create() {
-        const popupProxyHost = new PopupProxyHost();
-        popupProxyHost.prepare();
-        return popupProxyHost;
-    }
+    // Public functions
 
     async prepare() {
-        this.frameIdPromise = apiFrameInformationGet();
-        const {frameId} = await this.frameIdPromise;
+        this._frameIdPromise = apiFrameInformationGet();
+        const {frameId} = await this._frameIdPromise;
         if (typeof frameId !== 'number') { return; }
 
-        this.apiReceiver = new FrontendApiReceiver(`popup-proxy-host#${frameId}`, {
-            createNestedPopup: ({parentId}) => this.createNestedPopup(parentId),
-            setOptions: ({id, options}) => this.setOptions(id, options),
-            hide: ({id, changeFocus}) => this.hide(id, changeFocus),
-            isVisibleAsync: ({id}) => this.isVisibleAsync(id),
-            setVisibleOverride: ({id, visible}) => this.setVisibleOverride(id, visible),
-            containsPoint: ({id, x, y}) => this.containsPoint(id, x, y),
-            showContent: ({id, elementRect, writingMode, type, details}) => this.showContent(id, elementRect, writingMode, type, details),
-            setCustomCss: ({id, css}) => this.setCustomCss(id, css),
-            clearAutoPlayTimer: ({id}) => this.clearAutoPlayTimer(id)
-        });
+        this._apiReceiver = new FrontendApiReceiver(`popup-proxy-host#${frameId}`, new Map([
+            ['createNestedPopup', ({parentId}) => this._onApiCreateNestedPopup(parentId)],
+            ['setOptions', ({id, options}) => this._onApiSetOptions(id, options)],
+            ['hide', ({id, changeFocus}) => this._onApiHide(id, changeFocus)],
+            ['isVisible', ({id}) => this._onApiIsVisibleAsync(id)],
+            ['setVisibleOverride', ({id, visible}) => this._onApiSetVisibleOverride(id, visible)],
+            ['containsPoint', ({id, x, y}) => this._onApiContainsPoint(id, x, y)],
+            ['showContent', ({id, elementRect, writingMode, type, details}) => this._onApiShowContent(id, elementRect, writingMode, type, details)],
+            ['setCustomCss', ({id, css}) => this._onApiSetCustomCss(id, css)],
+            ['clearAutoPlayTimer', ({id}) => this._onApiClearAutoPlayTimer(id)]
+        ]));
     }
 
     createPopup(parentId, depth) {
-        const parent = (typeof parentId === 'string' && hasOwn(this.popups, parentId) ? this.popups[parentId] : null);
-        const id = `${this.nextId}`;
-        if (parent !== null) {
-            depth = parent.depth + 1;
-        }
-        ++this.nextId;
-        const popup = new Popup(id, depth, this.frameIdPromise);
-        if (parent !== null) {
-            popup.parent = parent;
-            parent.child = popup;
-        }
-        this.popups[id] = popup;
-        return popup;
-    }
-
-    async createNestedPopup(parentId) {
-        return this.createPopup(parentId, 0).id;
+        return this._createPopupInternal(parentId, depth).popup;
     }
 
-    getPopup(id) {
-        if (!hasOwn(this.popups, id)) {
-            throw new Error('Invalid popup ID');
-        }
-
-        return this.popups[id];
-    }
+    // Message handlers
 
-    jsonRectToDOMRect(popup, jsonRect) {
-        let x = jsonRect.x;
-        let y = jsonRect.y;
-        if (popup.parent !== null) {
-            const popupRect = popup.parent.container.getBoundingClientRect();
-            x += popupRect.x;
-            y += popupRect.y;
-        }
-        return new DOMRect(x, y, jsonRect.width, jsonRect.height);
+    async _onApiCreateNestedPopup(parentId) {
+        return this._createPopupInternal(parentId, 0).id;
     }
 
-    async setOptions(id, options) {
-        const popup = this.getPopup(id);
+    async _onApiSetOptions(id, options) {
+        const popup = this._getPopup(id);
         return await popup.setOptions(options);
     }
 
-    async hide(id, changeFocus) {
-        const popup = this.getPopup(id);
+    async _onApiHide(id, changeFocus) {
+        const popup = this._getPopup(id);
         return popup.hide(changeFocus);
     }
 
-    async isVisibleAsync(id) {
-        const popup = this.getPopup(id);
-        return await popup.isVisibleAsync();
+    async _onApiIsVisibleAsync(id) {
+        const popup = this._getPopup(id);
+        return await popup.isVisible();
     }
 
-    async setVisibleOverride(id, visible) {
-        const popup = this.getPopup(id);
+    async _onApiSetVisibleOverride(id, visible) {
+        const popup = this._getPopup(id);
         return await popup.setVisibleOverride(visible);
     }
 
-    async containsPoint(id, x, y) {
-        const popup = this.getPopup(id);
+    async _onApiContainsPoint(id, x, y) {
+        const popup = this._getPopup(id);
         return await popup.containsPoint(x, y);
     }
 
-    async showContent(id, elementRect, writingMode, type, details) {
-        const popup = this.getPopup(id);
-        elementRect = this.jsonRectToDOMRect(popup, elementRect);
-        if (!PopupProxyHost.popupCanShow(popup)) { return Promise.resolve(false); }
+    async _onApiShowContent(id, elementRect, writingMode, type, details) {
+        const popup = this._getPopup(id);
+        elementRect = PopupProxyHost._convertJsonRectToDOMRect(popup, elementRect);
+        if (!PopupProxyHost._popupCanShow(popup)) { return; }
         return await popup.showContent(elementRect, writingMode, type, details);
     }
 
-    async setCustomCss(id, css) {
-        const popup = this.getPopup(id);
+    async _onApiSetCustomCss(id, css) {
+        const popup = this._getPopup(id);
         return popup.setCustomCss(css);
     }
 
-    async clearAutoPlayTimer(id) {
-        const popup = this.getPopup(id);
+    async _onApiClearAutoPlayTimer(id) {
+        const popup = this._getPopup(id);
         return popup.clearAutoPlayTimer();
     }
 
-    static popupCanShow(popup) {
-        return popup.parent === null || popup.parent.isVisible();
+    // Private functions
+
+    _createPopupInternal(parentId, depth) {
+        const parent = (typeof parentId === 'string' && this._popups.has(parentId) ? this._popups.get(parentId) : null);
+        const id = `${this._nextId}`;
+        if (parent !== null) {
+            depth = parent.depth + 1;
+        }
+        ++this._nextId;
+        const popup = new Popup(id, depth, this._frameIdPromise);
+        if (parent !== null) {
+            popup.setParent(parent);
+        }
+        this._popups.set(id, popup);
+        return {popup, id};
     }
-}
 
-PopupProxyHost.instance = PopupProxyHost.create();
+    _getPopup(id) {
+        const popup = this._popups.get(id);
+        if (typeof popup === 'undefined') {
+            throw new Error('Invalid popup ID');
+        }
+        return popup;
+    }
+
+    static _convertJsonRectToDOMRect(popup, jsonRect) {
+        let x = jsonRect.x;
+        let y = jsonRect.y;
+        if (popup.parent !== null) {
+            const popupRect = popup.parent.getContainerRect();
+            x += popupRect.x;
+            y += popupRect.y;
+        }
+        return new DOMRect(x, y, jsonRect.width, jsonRect.height);
+    }
+
+    static _popupCanShow(popup) {
+        return popup.parent === null || popup.parent.isVisibleSync();
+    }
+}
diff --git a/ext/fg/js/popup-proxy.js b/ext/fg/js/popup-proxy.js
index e62a4868..ae0cffad 100644
--- a/ext/fg/js/popup-proxy.js
+++ b/ext/fg/js/popup-proxy.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2019-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,94 +13,113 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
 class PopupProxy {
     constructor(depth, parentId, parentFrameId, url) {
-        this.parentId = parentId;
-        this.parentFrameId = parentFrameId;
-        this.id = null;
-        this.idPromise = null;
-        this.parent = null;
-        this.child = null;
-        this.depth = depth;
-        this.url = url;
+        this._parentId = parentId;
+        this._parentFrameId = parentFrameId;
+        this._id = null;
+        this._idPromise = null;
+        this._depth = depth;
+        this._url = url;
+        this._apiSender = new FrontendApiSender();
+    }
 
-        this.container = null;
+    // Public properties
 
-        this.apiSender = new FrontendApiSender();
+    get parent() {
+        return null;
     }
 
-    getPopupId() {
-        if (this.idPromise === null) {
-            this.idPromise = this.getPopupIdAsync();
-        }
-        return this.idPromise;
+    get depth() {
+        return this._depth;
     }
 
-    async getPopupIdAsync() {
-        const id = await this.invokeHostApi('createNestedPopup', {parentId: this.parentId});
-        this.id = id;
-        return id;
+    get url() {
+        return this._url;
+    }
+
+    // Public functions
+
+    isProxy() {
+        return true;
     }
 
     async setOptions(options) {
-        const id = await this.getPopupId();
-        return await this.invokeHostApi('setOptions', {id, options});
+        const id = await this._getPopupId();
+        return await this._invokeHostApi('setOptions', {id, options});
     }
 
-    async hide(changeFocus) {
-        if (this.id === null) {
+    hide(changeFocus) {
+        if (this._id === null) {
             return;
         }
-        return await this.invokeHostApi('hide', {id: this.id, changeFocus});
+        this._invokeHostApi('hide', {id: this._id, changeFocus});
     }
 
-    async isVisibleAsync() {
-        const id = await this.getPopupId();
-        return await this.invokeHostApi('isVisibleAsync', {id});
+    async isVisible() {
+        const id = await this._getPopupId();
+        return await this._invokeHostApi('isVisible', {id});
     }
 
-    async setVisibleOverride(visible) {
-        const id = await this.getPopupId();
-        return await this.invokeHostApi('setVisibleOverride', {id, visible});
+    setVisibleOverride(visible) {
+        if (this._id === null) {
+            return;
+        }
+        this._invokeHostApi('setVisibleOverride', {id, visible});
     }
 
     async containsPoint(x, y) {
-        if (this.id === null) {
+        if (this._id === null) {
             return false;
         }
-        return await this.invokeHostApi('containsPoint', {id: this.id, x, y});
+        return await this._invokeHostApi('containsPoint', {id: this._id, x, y});
     }
 
     async showContent(elementRect, writingMode, type=null, details=null) {
-        const id = await this.getPopupId();
-        elementRect = PopupProxy.DOMRectToJson(elementRect);
-        return await this.invokeHostApi('showContent', {id, elementRect, writingMode, type, details});
+        const id = await this._getPopupId();
+        elementRect = PopupProxy._convertDOMRectToJson(elementRect);
+        return await this._invokeHostApi('showContent', {id, elementRect, writingMode, type, details});
     }
 
     async setCustomCss(css) {
-        const id = await this.getPopupId();
-        return await this.invokeHostApi('setCustomCss', {id, css});
+        const id = await this._getPopupId();
+        return await this._invokeHostApi('setCustomCss', {id, css});
     }
 
-    async clearAutoPlayTimer() {
-        if (this.id === null) {
+    clearAutoPlayTimer() {
+        if (this._id === null) {
             return;
         }
-        return await this.invokeHostApi('clearAutoPlayTimer', {id: this.id});
+        this._invokeHostApi('clearAutoPlayTimer', {id: this._id});
+    }
+
+    // Private
+
+    _getPopupId() {
+        if (this._idPromise === null) {
+            this._idPromise = this._getPopupIdAsync();
+        }
+        return this._idPromise;
+    }
+
+    async _getPopupIdAsync() {
+        const id = await this._invokeHostApi('createNestedPopup', {parentId: this._parentId});
+        this._id = id;
+        return id;
     }
 
-    invokeHostApi(action, params={}) {
-        if (typeof this.parentFrameId !== 'number') {
+    _invokeHostApi(action, params={}) {
+        if (typeof this._parentFrameId !== 'number') {
             return Promise.reject(new Error('Invalid frame'));
         }
-        return this.apiSender.invoke(action, params, `popup-proxy-host#${this.parentFrameId}`);
+        return this._apiSender.invoke(action, params, `popup-proxy-host#${this._parentFrameId}`);
     }
 
-    static DOMRectToJson(domRect) {
+    static _convertDOMRectToJson(domRect) {
         return {
             x: domRect.x,
             y: domRect.y,
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 42475d96..7a0c6133 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2017  Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2016-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,100 +13,241 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 
 class Popup {
     constructor(id, depth, frameIdPromise) {
-        this.id = id;
-        this.depth = depth;
-        this.frameIdPromise = frameIdPromise;
-        this.frameId = null;
-        this.parent = null;
-        this.child = null;
-        this.childrenSupported = true;
-        this.container = document.createElement('iframe');
-        this.container.className = 'yomichan-float';
-        this.container.addEventListener('mousedown', (e) => e.stopPropagation());
-        this.container.addEventListener('scroll', (e) => e.stopPropagation());
-        this.container.setAttribute('src', chrome.runtime.getURL('/fg/float.html'));
-        this.container.style.width = '0px';
-        this.container.style.height = '0px';
-        this.injectPromise = null;
-        this.isInjected = false;
-        this.visible = false;
-        this.visibleOverride = null;
-        this.options = null;
-        this.stylesheetInjectedViaApi = false;
-        this.updateVisibility();
-    }
-
-    inject() {
-        if (this.injectPromise === null) {
-            this.injectPromise = this.createInjectPromise();
+        this._id = id;
+        this._depth = depth;
+        this._frameIdPromise = frameIdPromise;
+        this._frameId = null;
+        this._parent = null;
+        this._child = null;
+        this._childrenSupported = true;
+        this._injectPromise = null;
+        this._isInjected = false;
+        this._visible = false;
+        this._visibleOverride = null;
+        this._options = null;
+        this._stylesheetInjectedViaApi = false;
+
+        this._container = document.createElement('iframe');
+        this._container.className = 'yomichan-float';
+        this._container.addEventListener('mousedown', (e) => e.stopPropagation());
+        this._container.addEventListener('scroll', (e) => e.stopPropagation());
+        this._container.setAttribute('src', chrome.runtime.getURL('/fg/float.html'));
+        this._container.style.width = '0px';
+        this._container.style.height = '0px';
+
+        this._updateVisibility();
+    }
+
+    // Public properties
+
+    get parent() {
+        return this._parent;
+    }
+
+    get depth() {
+        return this._depth;
+    }
+
+    get url() {
+        return window.location.href;
+    }
+
+    // Public functions
+
+    isProxy() {
+        return false;
+    }
+
+    async setOptions(options) {
+        this._options = options;
+        this.updateTheme();
+    }
+
+    hide(changeFocus) {
+        if (!this.isVisibleSync()) {
+            return;
+        }
+
+        this._setVisible(false);
+        if (this._child !== null) {
+            this._child.hide(false);
+        }
+        if (changeFocus) {
+            this._focusParent();
         }
-        return this.injectPromise;
     }
 
-    async createInjectPromise() {
+    async isVisible() {
+        return this.isVisibleSync();
+    }
+
+    setVisibleOverride(visible) {
+        this._visibleOverride = visible;
+        this._updateVisibility();
+    }
+
+    async containsPoint(x, y) {
+        for (let popup = this; popup !== null && popup.isVisibleSync(); popup = popup._child) {
+            const rect = popup._container.getBoundingClientRect();
+            if (x >= rect.left && y >= rect.top && x < rect.right && y < rect.bottom) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    async showContent(elementRect, writingMode, type=null, details=null) {
+        if (!this._isInitialized()) { return; }
+        await this._show(elementRect, writingMode);
+        if (type === null) { return; }
+        this._invokeApi('setContent', {type, details});
+    }
+
+    async setCustomCss(css) {
+        this._invokeApi('setCustomCss', {css});
+    }
+
+    clearAutoPlayTimer() {
+        if (this._isInjected) {
+            this._invokeApi('clearAutoPlayTimer');
+        }
+    }
+
+    // Popup-only public functions
+
+    setParent(parent) {
+        if (parent === null) {
+            throw new Error('Cannot set popup parent to null');
+        }
+        if (this._parent !== null) {
+            throw new Error('Popup already has a parent');
+        }
+        if (parent._child !== null) {
+            throw new Error('Cannot parent popup to another popup which already has a child');
+        }
+        this._parent = parent;
+        parent._child = this;
+    }
+
+    isVisibleSync() {
+        return this._isInjected && (this._visibleOverride !== null ? this._visibleOverride : this._visible);
+    }
+
+    updateTheme() {
+        this._container.dataset.yomichanTheme = this._options.general.popupOuterTheme;
+        this._container.dataset.yomichanSiteColor = this._getSiteColor();
+    }
+
+    async setCustomOuterCss(css, injectDirectly) {
+        // Cannot repeatedly inject stylesheets using web extension APIs since there is no way to remove them.
+        if (this._stylesheetInjectedViaApi) { return; }
+
+        if (injectDirectly || Popup._isOnExtensionPage()) {
+            Popup.injectOuterStylesheet(css);
+        } else {
+            if (!css) { return; }
+            try {
+                await apiInjectStylesheet(css);
+                this._stylesheetInjectedViaApi = true;
+            } catch (e) {
+                // NOP
+            }
+        }
+    }
+
+    setChildrenSupported(value) {
+        this._childrenSupported = value;
+    }
+
+    getContainer() {
+        return this._container;
+    }
+
+    getContainerRect() {
+        return this._container.getBoundingClientRect();
+    }
+
+    static injectOuterStylesheet(css) {
+        if (Popup.outerStylesheet === null) {
+            if (!css) { return; }
+            Popup.outerStylesheet = document.createElement('style');
+            Popup.outerStylesheet.id = 'yomichan-popup-outer-stylesheet';
+        }
+
+        const outerStylesheet = Popup.outerStylesheet;
+        if (css) {
+            outerStylesheet.textContent = css;
+
+            const par = document.head;
+            if (par && outerStylesheet.parentNode !== par) {
+                par.appendChild(outerStylesheet);
+            }
+        } else {
+            outerStylesheet.textContent = '';
+        }
+    }
+
+    // Private functions
+
+    _inject() {
+        if (this._injectPromise === null) {
+            this._injectPromise = this._createInjectPromise();
+        }
+        return this._injectPromise;
+    }
+
+    async _createInjectPromise() {
         try {
-            const {frameId} = await this.frameIdPromise;
+            const {frameId} = await this._frameIdPromise;
             if (typeof frameId === 'number') {
-                this.frameId = frameId;
+                this._frameId = frameId;
             }
         } catch (e) {
             // NOP
         }
 
         return new Promise((resolve) => {
-            const parentFrameId = (typeof this.frameId === 'number' ? this.frameId : null);
-            this.container.addEventListener('load', () => {
-                this.invokeApi('initialize', {
-                    options: this.options,
+            const parentFrameId = (typeof this._frameId === 'number' ? this._frameId : null);
+            this._container.addEventListener('load', () => {
+                this._invokeApi('initialize', {
+                    options: this._options,
                     popupInfo: {
-                        id: this.id,
-                        depth: this.depth,
+                        id: this._id,
+                        depth: this._depth,
                         parentFrameId
                     },
                     url: this.url,
-                    childrenSupported: this.childrenSupported
+                    childrenSupported: this._childrenSupported
                 });
                 resolve();
             });
-            this.observeFullscreen();
-            this.onFullscreenChanged();
-            this.setCustomOuterCss(this.options.general.customPopupOuterCss, false);
-            this.isInjected = true;
+            this._observeFullscreen();
+            this._onFullscreenChanged();
+            this.setCustomOuterCss(this._options.general.customPopupOuterCss, false);
+            this._isInjected = true;
         });
     }
 
-    isInitialized() {
-        return this.options !== null;
+    _isInitialized() {
+        return this._options !== null;
     }
 
-    async setOptions(options) {
-        this.options = options;
-        this.updateTheme();
-    }
+    async _show(elementRect, writingMode) {
+        await this._inject();
 
-    async showContent(elementRect, writingMode, type=null, details=null) {
-        if (!this.isInitialized()) { return; }
-        await this.show(elementRect, writingMode);
-        if (type === null) { return; }
-        this.invokeApi('setContent', {type, details});
-    }
-
-    async show(elementRect, writingMode) {
-        await this.inject();
-
-        const optionsGeneral = this.options.general;
-        const container = this.container;
+        const optionsGeneral = this._options.general;
+        const container = this._container;
         const containerRect = container.getBoundingClientRect();
         const getPosition = (
             writingMode === 'horizontal-tb' || optionsGeneral.popupVerticalTextPosition === 'default' ?
-            Popup.getPositionForHorizontalText :
-            Popup.getPositionForVerticalText
+            Popup._getPositionForHorizontalText :
+            Popup._getPositionForVerticalText
         );
 
         const [x, y, width, height, below] = getPosition(
@@ -126,13 +267,78 @@ class Popup {
         container.style.width = `${width}px`;
         container.style.height = `${height}px`;
 
-        this.setVisible(true);
-        if (this.child !== null) {
-            this.child.hide(true);
+        this._setVisible(true);
+        if (this._child !== null) {
+            this._child.hide(true);
+        }
+    }
+
+    _setVisible(visible) {
+        this._visible = visible;
+        this._updateVisibility();
+    }
+
+    _updateVisibility() {
+        this._container.style.setProperty('visibility', this.isVisibleSync() ? 'visible' : 'hidden', 'important');
+    }
+
+    _focusParent() {
+        if (this._parent !== null) {
+            // Chrome doesn't like focusing iframe without contentWindow.
+            const contentWindow = this._parent._container.contentWindow;
+            if (contentWindow !== null) {
+                contentWindow.focus();
+            }
+        } else {
+            // Firefox doesn't like focusing window without first blurring the iframe.
+            // this.container.contentWindow.blur() doesn't work on Firefox for some reason.
+            this._container.blur();
+            // This is needed for Chrome.
+            window.focus();
+        }
+    }
+
+    _getSiteColor() {
+        const color = [255, 255, 255];
+        Popup._addColor(color, Popup._getColorInfo(window.getComputedStyle(document.documentElement).backgroundColor));
+        Popup._addColor(color, Popup._getColorInfo(window.getComputedStyle(document.body).backgroundColor));
+        const dark = (color[0] < 128 && color[1] < 128 && color[2] < 128);
+        return dark ? 'dark' : 'light';
+    }
+
+    _invokeApi(action, params={}) {
+        this._container.contentWindow.postMessage({action, params}, '*');
+    }
+
+    _observeFullscreen() {
+        const fullscreenEvents = [
+            'fullscreenchange',
+            'MSFullscreenChange',
+            'mozfullscreenchange',
+            'webkitfullscreenchange'
+        ];
+        for (const eventName of fullscreenEvents) {
+            document.addEventListener(eventName, () => this._onFullscreenChanged(), false);
         }
     }
 
-    static getPositionForHorizontalText(elementRect, width, height, maxWidth, maxHeight, optionsGeneral) {
+    _getFullscreenElement() {
+        return (
+            document.fullscreenElement ||
+            document.msFullscreenElement ||
+            document.mozFullScreenElement ||
+            document.webkitFullscreenElement
+        );
+    }
+
+    _onFullscreenChanged() {
+        const parent = (this._getFullscreenElement() || document.body || null);
+        if (parent !== null && this._container.parentNode !== parent) {
+            parent.appendChild(this._container);
+        }
+    }
+
+    static _getPositionForHorizontalText(elementRect, width, height, maxWidth, maxHeight, optionsGeneral) {
         let x = elementRect.left + optionsGeneral.popupHorizontalOffset;
         const overflowX = Math.max(x + width - maxWidth, 0);
         if (overflowX > 0) {
@@ -147,7 +353,7 @@ class Popup {
         const preferBelow = (optionsGeneral.popupHorizontalTextPosition === 'below');
 
         const verticalOffset = optionsGeneral.popupVerticalOffset;
-        const [y, h, below] = Popup.limitGeometry(
+        const [y, h, below] = Popup._limitGeometry(
             elementRect.top - verticalOffset,
             elementRect.bottom + verticalOffset,
             height,
@@ -158,19 +364,19 @@ class Popup {
         return [x, y, width, h, below];
     }
 
-    static getPositionForVerticalText(elementRect, width, height, maxWidth, maxHeight, optionsGeneral, writingMode) {
-        const preferRight = Popup.isVerticalTextPopupOnRight(optionsGeneral.popupVerticalTextPosition, writingMode);
+    static _getPositionForVerticalText(elementRect, width, height, maxWidth, maxHeight, optionsGeneral, writingMode) {
+        const preferRight = Popup._isVerticalTextPopupOnRight(optionsGeneral.popupVerticalTextPosition, writingMode);
         const horizontalOffset = optionsGeneral.popupHorizontalOffset2;
         const verticalOffset = optionsGeneral.popupVerticalOffset2;
 
-        const [x, w] = Popup.limitGeometry(
+        const [x, w] = Popup._limitGeometry(
             elementRect.left - horizontalOffset,
             elementRect.right + horizontalOffset,
             width,
             maxWidth,
             preferRight
         );
-        const [y, h, below] = Popup.limitGeometry(
+        const [y, h, below] = Popup._limitGeometry(
             elementRect.bottom - verticalOffset,
             elementRect.top + verticalOffset,
             height,
@@ -180,12 +386,12 @@ class Popup {
         return [x, y, w, h, below];
     }
 
-    static isVerticalTextPopupOnRight(positionPreference, writingMode) {
+    static _isVerticalTextPopupOnRight(positionPreference, writingMode) {
         switch (positionPreference) {
             case 'before':
-                return !Popup.isWritingModeLeftToRight(writingMode);
+                return !Popup._isWritingModeLeftToRight(writingMode);
             case 'after':
-                return Popup.isWritingModeLeftToRight(writingMode);
+                return Popup._isWritingModeLeftToRight(writingMode);
             case 'left':
                 return false;
             case 'right':
@@ -193,7 +399,7 @@ class Popup {
         }
     }
 
-    static isWritingModeLeftToRight(writingMode) {
+    static _isWritingModeLeftToRight(writingMode) {
         switch (writingMode) {
             case 'vertical-lr':
             case 'sideways-lr':
@@ -203,7 +409,7 @@ class Popup {
         }
     }
 
-    static limitGeometry(positionBefore, positionAfter, size, limit, preferAfter) {
+    static _limitGeometry(positionBefore, positionAfter, size, limit, preferAfter) {
         let after = preferAfter;
         let position = 0;
         const overflowBefore = Math.max(0, size - positionBefore);
@@ -225,72 +431,7 @@ class Popup {
         return [position, size, after];
     }
 
-    hide(changeFocus) {
-        if (!this.isVisible()) {
-            return;
-        }
-
-        this.setVisible(false);
-        if (this.child !== null) {
-            this.child.hide(false);
-        }
-        if (changeFocus) {
-            this.focusParent();
-        }
-    }
-
-    async isVisibleAsync() {
-        return this.isVisible();
-    }
-
-    isVisible() {
-        return this.isInjected && (this.visibleOverride !== null ? this.visibleOverride : this.visible);
-    }
-
-    setVisible(visible) {
-        this.visible = visible;
-        this.updateVisibility();
-    }
-
-    setVisibleOverride(visible) {
-        this.visibleOverride = visible;
-        this.updateVisibility();
-    }
-
-    updateVisibility() {
-        this.container.style.setProperty('visibility', this.isVisible() ? 'visible' : 'hidden', 'important');
-    }
-
-    focusParent() {
-        if (this.parent !== null) {
-            // Chrome doesn't like focusing iframe without contentWindow.
-            const contentWindow = this.parent.container.contentWindow;
-            if (contentWindow !== null) {
-                contentWindow.focus();
-            }
-        } else {
-            // Firefox doesn't like focusing window without first blurring the iframe.
-            // this.container.contentWindow.blur() doesn't work on Firefox for some reason.
-            this.container.blur();
-            // This is needed for Chrome.
-            window.focus();
-        }
-    }
-
-    updateTheme() {
-        this.container.dataset.yomichanTheme = this.options.general.popupOuterTheme;
-        this.container.dataset.yomichanSiteColor = this.getSiteColor();
-    }
-
-    getSiteColor() {
-        const color = [255, 255, 255];
-        Popup.addColor(color, Popup.getColorInfo(window.getComputedStyle(document.documentElement).backgroundColor));
-        Popup.addColor(color, Popup.getColorInfo(window.getComputedStyle(document.body).backgroundColor));
-        const dark = (color[0] < 128 && color[1] < 128 && color[2] < 128);
-        return dark ? 'dark' : 'light';
-    }
-
-    static addColor(target, color) {
+    static _addColor(target, color) {
         if (color === null) { return; }
 
         const a = color[3];
@@ -302,7 +443,7 @@ class Popup {
         }
     }
 
-    static getColorInfo(cssColor) {
+    static _getColorInfo(cssColor) {
         const m = /^\s*rgba?\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*(?:,\s*([\d.]+)\s*)?\)\s*$/.exec(cssColor);
         if (m === null) { return null; }
 
@@ -315,80 +456,7 @@ class Popup {
         ];
     }
 
-    async containsPoint(x, y) {
-        for (let popup = this; popup !== null && popup.isVisible(); popup = popup.child) {
-            const rect = popup.container.getBoundingClientRect();
-            if (x >= rect.left && y >= rect.top && x < rect.right && y < rect.bottom) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    async setCustomCss(css) {
-        this.invokeApi('setCustomCss', {css});
-    }
-
-    async setCustomOuterCss(css, injectDirectly) {
-        // Cannot repeatedly inject stylesheets using web extension APIs since there is no way to remove them.
-        if (this.stylesheetInjectedViaApi) { return; }
-
-        if (injectDirectly || Popup.isOnExtensionPage()) {
-            Popup.injectOuterStylesheet(css);
-        } else {
-            if (!css) { return; }
-            try {
-                await apiInjectStylesheet(css);
-                this.stylesheetInjectedViaApi = true;
-            } catch (e) {
-                // NOP
-            }
-        }
-    }
-
-    clearAutoPlayTimer() {
-        if (this.isInjected) {
-            this.invokeApi('clearAutoPlayTimer');
-        }
-    }
-
-    invokeApi(action, params={}) {
-        this.container.contentWindow.postMessage({action, params}, '*');
-    }
-
-    observeFullscreen() {
-        const fullscreenEvents = [
-            'fullscreenchange',
-            'MSFullscreenChange',
-            'mozfullscreenchange',
-            'webkitfullscreenchange'
-        ];
-        for (const eventName of fullscreenEvents) {
-            document.addEventListener(eventName, () => this.onFullscreenChanged(), false);
-        }
-    }
-
-    getFullscreenElement() {
-        return (
-            document.fullscreenElement ||
-            document.msFullscreenElement ||
-            document.mozFullScreenElement ||
-            document.webkitFullscreenElement
-        );
-    }
-
-    onFullscreenChanged() {
-        const parent = (this.getFullscreenElement() || document.body || null);
-        if (parent !== null && this.container.parentNode !== parent) {
-            parent.appendChild(this.container);
-        }
-    }
-
-    get url() {
-        return window.location.href;
-    }
-
-    static isOnExtensionPage() {
+    static _isOnExtensionPage() {
         try {
             const url = chrome.runtime.getURL('/');
             return window.location.href.substring(0, url.length) === url;
@@ -396,26 +464,6 @@ class Popup {
             // NOP
         }
     }
-
-    static injectOuterStylesheet(css) {
-        if (Popup.outerStylesheet === null) {
-            if (!css) { return; }
-            Popup.outerStylesheet = document.createElement('style');
-            Popup.outerStylesheet.id = 'yomichan-popup-outer-stylesheet';
-        }
-
-        const outerStylesheet = Popup.outerStylesheet;
-        if (css) {
-            outerStylesheet.textContent = css;
-
-            const par = document.head;
-            if (par && outerStylesheet.parentNode !== par) {
-                par.appendChild(outerStylesheet);
-            }
-        } else {
-            outerStylesheet.textContent = '';
-        }
-    }
 }
 
 Popup.outerStylesheet = null;
diff --git a/ext/fg/js/source.js b/ext/fg/js/source.js
index a84feed4..5cdf47b5 100644
--- a/ext/fg/js/source.js
+++ b/ext/fg/js/source.js
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2017  Alex Yatskov <alex@foosoft.net>
+ * Copyright (C) 2016-2020  Alex Yatskov <alex@foosoft.net>
  * Author: Alex Yatskov <alex@foosoft.net>
  *
  * This program is free software: you can redistribute it and/or modify
@@ -13,7 +13,7 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
 // \u200c (Zero-width non-joiner) appears on Google Docs from Chrome 76 onwards