22 files changed, 814 insertions, 44 deletions

diff --git a/ext/bg/background.html b/ext/bg/background.html
index 5978f10f..90a56024 100644
--- a/ext/bg/background.html
+++ b/ext/bg/background.html
@@ -15,6 +15,7 @@
         <script src="/bg/js/anki.js"></script>
         <script src="/bg/js/api.js"></script>
         <script src="/bg/js/audio.js"></script>
+        <script src="/bg/js/backend-api-forwarder.js"></script>
         <script src="/bg/js/database.js"></script>
         <script src="/bg/js/deinflector.js"></script>
         <script src="/bg/js/dictionary.js"></script>
diff --git a/ext/bg/js/api.js b/ext/bg/js/api.js
index 4b2bacd7..b8ef4362 100644
--- a/ext/bg/js/api.js
+++ b/ext/bg/js/api.js
@@ -205,3 +205,8 @@ function apiForward(action, params, sender) {
         chrome.tabs.sendMessage(tabId, {action, params}, (response) => resolve(response));
     });
 }
+
+function apiFrameInformationGet(sender) {
+    const frameId = sender.frameId;
+    return Promise.resolve({frameId});
+}
diff --git a/ext/bg/js/backend-api-forwarder.js b/ext/bg/js/backend-api-forwarder.js
new file mode 100644
index 00000000..979afd16
--- /dev/null
+++ b/ext/bg/js/backend-api-forwarder.js
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+class BackendApiForwarder {
+    constructor() {
+        chrome.runtime.onConnect.addListener(this.onConnect.bind(this));
+    }
+
+    onConnect(port) {
+        if (port.name !== 'backend-api-forwarder') { return; }
+
+        let tabId;
+        if (!(
+            port.sender &&
+            port.sender.tab &&
+            (typeof (tabId = port.sender.tab.id)) === 'number'
+        )) {
+            port.disconnect();
+            return;
+        }
+
+        const forwardPort = chrome.tabs.connect(tabId, {name: 'frontend-api-receiver'});
+
+        port.onMessage.addListener(message => forwardPort.postMessage(message));
+        forwardPort.onMessage.addListener(message => port.postMessage(message));
+        port.onDisconnect.addListener(() => forwardPort.disconnect());
+        forwardPort.onDisconnect.addListener(() => port.disconnect());
+    }
+}
diff --git a/ext/bg/js/backend.js b/ext/bg/js/backend.js
index d95cb82d..39fd4288 100644
--- a/ext/bg/js/backend.js
+++ b/ext/bg/js/backend.js
@@ -22,6 +22,8 @@ class Backend {
         this.translator = new Translator();
         this.anki = new AnkiNull();
         this.options = null;
+
+        this.apiForwarder = new BackendApiForwarder();
     }
 
     async prepare() {
@@ -125,6 +127,10 @@ class Backend {
 
             forward: ({action, params}) => {
                 forward(apiForward(action, params, sender), callback);
+            },
+
+            frameInformationGet: () => {
+                forward(apiFrameInformationGet(sender), callback);
             }
         };
 
diff --git a/ext/bg/js/options.js b/ext/bg/js/options.js
index 7d993987..df95aae9 100644
--- a/ext/bg/js/options.js
+++ b/ext/bg/js/options.js
@@ -219,7 +219,10 @@ function optionsSetDefaults(options) {
             delay: 20,
             length: 10,
             modifier: 'shift',
-            deepDomScan: false
+            deepDomScan: false,
+            popupNestingMaxDepth: 0,
+            enableOnPopupExpressions: false,
+            enableOnSearchPage: true
         },
 
         dictionaries: {},
diff --git a/ext/bg/js/search-frontend.js b/ext/bg/js/search-frontend.js
new file mode 100644
index 00000000..840a1ea8
--- /dev/null
+++ b/ext/bg/js/search-frontend.js
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+async function searchFrontendSetup() {
+    const options = await apiOptionsGet();
+    if (!options.scanning.enableOnSearchPage) { return; }
+
+    const scriptSrcs = [
+        '/fg/js/api.js',
+        '/fg/js/frontend-api-receiver.js',
+        '/fg/js/popup.js',
+        '/fg/js/util.js',
+        '/fg/js/popup-proxy-host.js',
+        '/fg/js/frontend.js'
+    ];
+    for (const src of scriptSrcs) {
+        const script = document.createElement('script');
+        script.async = false;
+        script.src = src;
+        document.body.appendChild(script);
+    }
+
+    const styleSrcs = [
+        '/fg/css/client.css'
+    ];
+    for (const src of styleSrcs) {
+        const style = document.createElement('link');
+        style.rel = 'stylesheet';
+        style.type = 'text/css';
+        style.href = src;
+        document.head.appendChild(style);
+    }
+}
+
+searchFrontendSetup();
diff --git a/ext/bg/js/settings.js b/ext/bg/js/settings.js
index f5d669b2..83f4528c 100644
--- a/ext/bg/js/settings.js
+++ b/ext/bg/js/settings.js
@@ -48,9 +48,12 @@ async function formRead() {
     optionsNew.scanning.alphanumeric = $('#search-alphanumeric').prop('checked');
     optionsNew.scanning.autoHideResults = $('#auto-hide-results').prop('checked');
     optionsNew.scanning.deepDomScan = $('#deep-dom-scan').prop('checked');
+    optionsNew.scanning.enableOnPopupExpressions = $('#enable-scanning-of-popup-expressions').prop('checked');
+    optionsNew.scanning.enableOnSearchPage = $('#enable-scanning-on-search-page').prop('checked');
     optionsNew.scanning.delay = parseInt($('#scan-delay').val(), 10);
     optionsNew.scanning.length = parseInt($('#scan-length').val(), 10);
     optionsNew.scanning.modifier = $('#scan-modifier-key').val();
+    optionsNew.scanning.popupNestingMaxDepth = parseInt($('#popup-nesting-max-depth').val(), 10);
 
     optionsNew.anki.enable = $('#anki-enable').prop('checked');
     optionsNew.anki.tags = $('#card-tags').val().split(/[,; ]+/);
@@ -189,9 +192,12 @@ async function onReady() {
     $('#search-alphanumeric').prop('checked', options.scanning.alphanumeric);
     $('#auto-hide-results').prop('checked', options.scanning.autoHideResults);
     $('#deep-dom-scan').prop('checked', options.scanning.deepDomScan);
+    $('#enable-scanning-of-popup-expressions').prop('checked', options.scanning.enableOnPopupExpressions);
+    $('#enable-scanning-on-search-page').prop('checked', options.scanning.enableOnSearchPage);
     $('#scan-delay').val(options.scanning.delay);
     $('#scan-length').val(options.scanning.length);
     $('#scan-modifier-key').val(options.scanning.modifier);
+    $('#popup-nesting-max-depth').val(options.scanning.popupNestingMaxDepth);
 
     $('#dict-purge-link').click(utilAsync(onDictionaryPurge));
     $('#dict-file').change(utilAsync(onDictionaryImport));
diff --git a/ext/bg/search.html b/ext/bg/search.html
index 05c0daab..38c5a4e9 100644
--- a/ext/bg/search.html
+++ b/ext/bg/search.html
@@ -51,5 +51,6 @@
         <script src="/mixed/js/japanese.js"></script>
 
         <script src="/bg/js/search.js"></script>
+        <script src="/bg/js/search-frontend.js"></script>
     </body>
 </html>
diff --git a/ext/bg/settings.html b/ext/bg/settings.html
index cc140023..85b7ee5f 100644
--- a/ext/bg/settings.html
+++ b/ext/bg/settings.html
@@ -193,6 +193,14 @@
                 </div>
 
                 <div class="checkbox options-advanced">
+                    <label><input type="checkbox" id="enable-scanning-of-popup-expressions"> Enable scanning of popup expressions</label>
+                </div>
+
+                <div class="checkbox">
+                    <label><input type="checkbox" id="enable-scanning-on-search-page"> Enable scanning on search page</label>
+                </div>
+
+                <div class="checkbox options-advanced">
                     <label><input type="checkbox" id="deep-dom-scan"> Deep DOM scan</label>
                 </div>
 
@@ -215,6 +223,11 @@
                         <option value="shift">Shift</option>
                     </select>
                 </div>
+
+                <div class="form-group options-advanced">
+                    <label for="popup-nesting-max-depth">Maximum nested popup depth</label>
+                    <input type="number" min="0" id="popup-nesting-max-depth" class="form-control">
+                </div>
             </div>
 
             <div>
diff --git a/ext/fg/float.html b/ext/fg/float.html
index 0133e653..465db589 100644
--- a/ext/fg/float.html
+++ b/ext/fg/float.html
@@ -43,5 +43,7 @@
         <script src="/mixed/js/display.js"></script>
 
         <script src="/fg/js/float.js"></script>
+
+        <script src="/fg/js/popup-nested.js"></script>
     </body>
 </html>
diff --git a/ext/fg/js/api.js b/ext/fg/js/api.js
index 99ad307c..6bcb0dbb 100644
--- a/ext/fg/js/api.js
+++ b/ext/fg/js/api.js
@@ -64,3 +64,7 @@ function apiScreenshotGet(options) {
 function apiForward(action, params) {
     return utilInvoke('forward', {action, params});
 }
+
+function apiFrameInformationGet() {
+    return utilInvoke('frameInformationGet');
+}
diff --git a/ext/fg/js/float.js b/ext/fg/js/float.js
index c0ec8a15..3c521714 100644
--- a/ext/fg/js/float.js
+++ b/ext/fg/js/float.js
@@ -72,6 +72,10 @@ class DisplayFloat extends Display {
                 if (css) {
                     this.setStyle(css);
                 }
+            },
+
+            popupNestedInitialize: ({id, depth, parentFrameId}) => {
+                popupNestedInitialize(id, depth, parentFrameId);
             }
         };
 
diff --git a/ext/fg/js/frontend-api-receiver.js b/ext/fg/js/frontend-api-receiver.js
new file mode 100644
index 00000000..687e5c3c
--- /dev/null
+++ b/ext/fg/js/frontend-api-receiver.js
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+class FrontendApiReceiver {
+    constructor(source='', handlers={}) {
+        this.source = source;
+        this.handlers = handlers;
+
+        chrome.runtime.onConnect.addListener(this.onConnect.bind(this));
+    }
+
+    onConnect(port) {
+        if (port.name !== 'frontend-api-receiver') { return; }
+
+        port.onMessage.addListener(this.onMessage.bind(this, port));
+    }
+
+    onMessage(port, {id, action, params, target, senderId}) {
+        if (
+            target !== this.source ||
+            !this.handlers.hasOwnProperty(action)
+        ) {
+            return;
+        }
+
+        this.sendAck(port, id, senderId);
+
+        const handler = this.handlers[action];
+        handler(params).then(
+            result => {
+                this.sendResult(port, id, senderId, {result});
+            },
+            e => {
+                const error = typeof e.toString === 'function' ? e.toString() : e;
+                this.sendResult(port, id, senderId, {error});
+            });
+    }
+
+    sendAck(port, id, senderId) {
+        port.postMessage({type: 'ack', id, senderId});
+    }
+
+    sendResult(port, id, senderId, data) {
+        port.postMessage({type: 'result', id, senderId, data});
+    }
+}
diff --git a/ext/fg/js/frontend-api-sender.js b/ext/fg/js/frontend-api-sender.js
new file mode 100644
index 00000000..a1cb02c4
--- /dev/null
+++ b/ext/fg/js/frontend-api-sender.js
@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+class FrontendApiSender {
+    constructor() {
+        this.senderId = FrontendApiSender.generateId(16);
+        this.ackTimeout = 3000; // 3 seconds
+        this.responseTimeout = 10000; // 10 seconds
+        this.callbacks = {};
+        this.disconnected = false;
+        this.nextId = 0;
+
+        this.port = chrome.runtime.connect(null, {name: 'backend-api-forwarder'});
+        this.port.onDisconnect.addListener(this.onDisconnect.bind(this));
+        this.port.onMessage.addListener(this.onMessage.bind(this));
+    }
+
+    invoke(action, params, target) {
+        if (this.disconnected) {
+            return Promise.reject('Disconnected');
+        }
+
+        const id = `${this.nextId}`;
+        ++this.nextId;
+
+        return new Promise((resolve, reject) => {
+            const info = {id, resolve, reject, ack: false, timer: null};
+            this.callbacks[id] = info;
+            info.timer = setTimeout(() => this.onError(id, 'Timeout (ack)'), this.ackTimeout);
+
+            this.port.postMessage({id, action, params, target, senderId: this.senderId});
+        });
+    }
+
+    onMessage({type, id, data, senderId}) {
+        if (senderId !== this.senderId) { return; }
+        switch (type) {
+            case 'ack':
+                this.onAck(id);
+                break;
+            case 'result':
+                this.onResult(id, data);
+                break;
+        }
+    }
+
+    onDisconnect() {
+        this.disconnected = true;
+
+        const ids = Object.keys(this.callbacks);
+        for (const id of ids) {
+            this.onError(id, 'Disconnected');
+        }
+    }
+
+    onAck(id) {
+        if (!this.callbacks.hasOwnProperty(id)) {
+            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;
+        }
+
+        info.ack = true;
+        clearTimeout(info.timer);
+        info.timer = setTimeout(() => this.onError(id, 'Timeout (response)'), this.responseTimeout);
+    }
+
+    onResult(id, data) {
+        if (!this.callbacks.hasOwnProperty(id)) {
+            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];
+        clearTimeout(info.timer);
+        info.timer = null;
+
+        if (typeof data.error === 'string') {
+            info.reject(data.error);
+        } else {
+            info.resolve(data.result);
+        }
+    }
+
+    onError(id, reason) {
+        if (!this.callbacks.hasOwnProperty(id)) { return; }
+        const info = this.callbacks[id];
+        delete this.callbacks[id];
+        info.timer = null;
+        info.reject(reason);
+    }
+
+    static generateId(length) {
+        let id = '';
+        for (let i = 0; i < length; ++i) {
+            id += Math.floor(Math.random() * 256).toString(16).padStart(2, '0');
+        }
+        return id;
+    }
+}
diff --git a/ext/fg/js/frontend.js b/ext/fg/js/frontend.js
index 8a5c48d0..b70bf036 100644
--- a/ext/fg/js/frontend.js
+++ b/ext/fg/js/frontend.js
@@ -18,14 +18,15 @@
 
 
 class Frontend {
-    constructor() {
-        this.popup = new Popup();
+    constructor(popup, ignoreNodes) {
+        this.popup = popup;
         this.popupTimer = null;
         this.mouseDownLeft = false;
         this.mouseDownMiddle = false;
         this.textSourceLast = null;
         this.pendingLookup = false;
         this.options = null;
+        this.ignoreNodes = (Array.isArray(ignoreNodes) && ignoreNodes.length > 0 ? ignoreNodes.join(',') : null);
 
         this.primaryTouchIdentifier = null;
         this.contextMenuChecking = false;
@@ -36,6 +37,17 @@ class Frontend {
         this.scrollPrevent = false;
     }
 
+    static create() {
+        const initializationData = window.frontendInitializationData;
+        const isNested = (initializationData !== null && typeof initializationData === 'object');
+        const {id, parentFrameId, ignoreNodes} = isNested ? initializationData : {};
+
+        const popup = isNested ? new PopupProxy(id, parentFrameId) : PopupProxyHost.instance.createPopup(null);
+        const frontend = new Frontend(popup, ignoreNodes);
+        frontend.prepare();
+        return frontend;
+    }
+
     async prepare() {
         try {
             this.options = await apiOptionsGet();
@@ -44,6 +56,7 @@ class Frontend {
             window.addEventListener('mousedown', this.onMouseDown.bind(this));
             window.addEventListener('mousemove', this.onMouseMove.bind(this));
             window.addEventListener('mouseover', this.onMouseOver.bind(this));
+            window.addEventListener('mouseout', this.onMouseOut.bind(this));
             window.addEventListener('mouseup', this.onMouseUp.bind(this));
             window.addEventListener('resize', this.onResize.bind(this));
 
@@ -137,6 +150,10 @@ class Frontend {
         }
     }
 
+    onMouseOut(e) {
+        this.popupTimerClear();
+    }
+
     onFrameMessage(e) {
         const handlers = {
             popupClose: () => {
@@ -259,9 +276,8 @@ class Frontend {
         const handler = handlers[action];
         if (handler) {
             handler(params);
+            callback();
         }
-
-        callback();
     }
 
     onError(error) {
@@ -281,7 +297,7 @@ class Frontend {
     }
 
     async searchAt(point, type) {
-        if (this.pendingLookup || this.popup.containsPoint(point)) {
+        if (this.pendingLookup || await this.popup.containsPoint(point)) {
             return;
         }
 
@@ -324,9 +340,14 @@ class Frontend {
     }
 
     async searchTerms(textSource, focus) {
-        textSource.setEndOffset(this.options.scanning.length);
+        this.setTextSourceScanLength(textSource, this.options.scanning.length);
 
-        const {definitions, length} = await apiTermsFind(textSource.text());
+        const searchText = textSource.text();
+        if (searchText.length === 0) {
+            return;
+        }
+
+        const {definitions, length} = await apiTermsFind(searchText);
         if (definitions.length === 0) {
             return false;
         }
@@ -352,9 +373,14 @@ class Frontend {
     }
 
     async searchKanji(textSource, focus) {
-        textSource.setEndOffset(1);
+        this.setTextSourceScanLength(textSource, 1);
 
-        const definitions = await apiKanjiFind(textSource.text());
+        const searchText = textSource.text();
+        if (searchText.length === 0) {
+            return;
+        }
+
+        const definitions = await apiKanjiFind(searchText);
         if (definitions.length === 0) {
             return false;
         }
@@ -480,7 +506,23 @@ class Frontend {
         }
         return false;
     }
+
+    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);
+        }
+    }
 }
 
-window.yomichan_frontend = new Frontend();
-window.yomichan_frontend.prepare();
+window.yomichan_frontend = Frontend.create();
diff --git a/ext/fg/js/popup-nested.js b/ext/fg/js/popup-nested.js
new file mode 100644
index 00000000..e0376bb2
--- /dev/null
+++ b/ext/fg/js/popup-nested.js
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+let popupNestedInitialized = false;
+
+async function popupNestedInitialize(id, depth, parentFrameId) {
+    if (popupNestedInitialized) {
+        return;
+    }
+    popupNestedInitialized = true;
+
+    const options = await apiOptionsGet();
+    const popupNestingMaxDepth = options.scanning.popupNestingMaxDepth;
+
+    if (!(typeof popupNestingMaxDepth === 'number' && typeof depth === 'number' && depth < popupNestingMaxDepth)) {
+        return;
+    }
+
+    const ignoreNodes = options.scanning.enableOnPopupExpressions ? [] : [ '.expression', '.expression *' ];
+
+    window.frontendInitializationData = {id, depth, parentFrameId, ignoreNodes};
+
+    const scriptSrcs = [
+        '/fg/js/frontend-api-sender.js',
+        '/fg/js/popup.js',
+        '/fg/js/popup-proxy.js',
+        '/fg/js/frontend.js'
+    ];
+    for (const src of scriptSrcs) {
+        const script = document.createElement('script');
+        script.async = false;
+        script.src = src;
+        document.body.appendChild(script);
+    }
+}
diff --git a/ext/fg/js/popup-proxy-host.js b/ext/fg/js/popup-proxy-host.js
new file mode 100644
index 00000000..fa61aeb4
--- /dev/null
+++ b/ext/fg/js/popup-proxy-host.js
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+class PopupProxyHost {
+    constructor() {
+        this.popups = {};
+        this.nextId = 0;
+        this.apiReceiver = null;
+        this.frameIdPromise = null;
+    }
+
+    static create() {
+        const popupProxyHost = new PopupProxyHost();
+        popupProxyHost.prepare();
+        return popupProxyHost;
+    }
+
+    async prepare() {
+        this.frameIdPromise = apiFrameInformationGet();
+        const {frameId} = await this.frameIdPromise;
+        if (typeof frameId !== 'number') { return; }
+
+        this.apiReceiver = new FrontendApiReceiver(`popup-proxy-host#${frameId}`, {
+            createNestedPopup: ({parentId}) => this.createNestedPopup(parentId),
+            show: ({id, elementRect, options}) => this.show(id, elementRect, options),
+            showOrphaned: ({id, elementRect, options}) => this.show(id, elementRect, options),
+            hide: ({id}) => this.hide(id),
+            setVisible: ({id, visible}) => this.setVisible(id, visible),
+            containsPoint: ({id, point}) => this.containsPoint(id, point),
+            termsShow: ({id, elementRect, definitions, options, context}) => this.termsShow(id, elementRect, definitions, options, context),
+            kanjiShow: ({id, elementRect, definitions, options, context}) => this.kanjiShow(id, elementRect, definitions, options, context),
+            clearAutoPlayTimer: ({id}) => this.clearAutoPlayTimer(id)
+        });
+    }
+
+    createPopup(parentId) {
+        const parent = (typeof parentId === 'string' && this.popups.hasOwnProperty(parentId) ? this.popups[parentId] : null);
+        const depth = (parent !== null ? parent.depth + 1 : 0);
+        const id = `${this.nextId}`;
+        ++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).id;
+    }
+
+    getPopup(id) {
+        if (!this.popups.hasOwnProperty(id)) {
+            throw 'Invalid popup ID';
+        }
+
+        return this.popups[id];
+    }
+
+    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 show(id, elementRect, options) {
+        const popup = this.getPopup(id);
+        elementRect = this.jsonRectToDOMRect(popup, elementRect);
+        return await popup.show(elementRect, options);
+    }
+
+    async showOrphaned(id, elementRect, options) {
+        const popup = this.getPopup(id);
+        elementRect = this.jsonRectToDOMRect(popup, elementRect);
+        return await popup.showOrphaned(elementRect, options);
+    }
+
+    async hide(id) {
+        const popup = this.getPopup(id);
+        return popup.hide();
+    }
+
+    async setVisible(id, visible) {
+        const popup = this.getPopup(id);
+        return popup.setVisible(visible);
+    }
+
+    async containsPoint(id, point) {
+        const popup = this.getPopup(id);
+        return await popup.containsPoint(point);
+    }
+
+    async termsShow(id, elementRect, definitions, options, context) {
+        const popup = this.getPopup(id);
+        elementRect = this.jsonRectToDOMRect(popup, elementRect);
+        return await popup.termsShow(elementRect, definitions, options, context);
+    }
+
+    async kanjiShow(id, elementRect, definitions, options, context) {
+        const popup = this.getPopup(id);
+        elementRect = this.jsonRectToDOMRect(popup, elementRect);
+        return await popup.kanjiShow(elementRect, definitions, options, context);
+    }
+
+    async clearAutoPlayTimer(id) {
+        const popup = this.getPopup(id);
+        return popup.clearAutoPlayTimer();
+    }
+}
+
+PopupProxyHost.instance = PopupProxyHost.create();
diff --git a/ext/fg/js/popup-proxy.js b/ext/fg/js/popup-proxy.js
new file mode 100644
index 00000000..f6295079
--- /dev/null
+++ b/ext/fg/js/popup-proxy.js
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2019 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/>.
+ */
+
+
+class PopupProxy {
+    constructor(parentId, parentFrameId) {
+        this.parentId = parentId;
+        this.parentFrameId = parentFrameId;
+        this.id = null;
+        this.idPromise = null;
+        this.parent = null;
+        this.child = null;
+        this.depth = 0;
+
+        this.container = null;
+
+        this.apiSender = new FrontendApiSender();
+    }
+
+    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;
+    }
+
+    async show(elementRect, options) {
+        const id = await this.getPopupId();
+        elementRect = PopupProxy.DOMRectToJson(elementRect);
+        return await this.invokeHostApi('show', {id, elementRect, options});
+    }
+
+    async showOrphaned(elementRect, options) {
+        const id = await this.getPopupId();
+        elementRect = PopupProxy.DOMRectToJson(elementRect);
+        return await this.invokeHostApi('showOrphaned', {id, elementRect, options});
+    }
+
+    async hide() {
+        if (this.id === null) {
+            return;
+        }
+        return await this.invokeHostApi('hide', {id: this.id});
+    }
+
+    async setVisible(visible) {
+        const id = await this.getPopupId();
+        return await this.invokeHostApi('setVisible', {id, visible});
+    }
+
+    async containsPoint(point) {
+        if (this.id === null) {
+            return false;
+        }
+        return await this.invokeHostApi('containsPoint', {id: this.id, point});
+    }
+
+    async termsShow(elementRect, definitions, options, context) {
+        const id = await this.getPopupId();
+        elementRect = PopupProxy.DOMRectToJson(elementRect);
+        return await this.invokeHostApi('termsShow', {id, elementRect, definitions, options, context});
+    }
+
+    async kanjiShow(elementRect, definitions, options, context) {
+        const id = await this.getPopupId();
+        elementRect = PopupProxy.DOMRectToJson(elementRect);
+        return await this.invokeHostApi('kanjiShow', {id, elementRect, definitions, options, context});
+    }
+
+    async clearAutoPlayTimer() {
+        if (this.id === null) {
+            return;
+        }
+        return await this.invokeHostApi('clearAutoPlayTimer', {id: this.id});
+    }
+
+    invokeHostApi(action, params={}) {
+        if (typeof this.parentFrameId !== 'number') {
+            return Promise.reject('Invalid frame');
+        }
+        return this.apiSender.invoke(action, params, `popup-proxy-host#${this.parentFrameId}`);
+    }
+
+    static DOMRectToJson(domRect) {
+        return {
+            x: domRect.x,
+            y: domRect.y,
+            width: domRect.width,
+            height: domRect.height
+        };
+    }
+}
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index 86ce575d..1b15977b 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -18,7 +18,13 @@
 
 
 class Popup {
-    constructor() {
+    constructor(id, depth, frameIdPromise) {
+        this.id = id;
+        this.depth = depth;
+        this.frameIdPromise = frameIdPromise;
+        this.frameId = null;
+        this.parent = null;
+        this.child = null;
         this.container = document.createElement('iframe');
         this.container.id = 'yomichan-float';
         this.container.addEventListener('mousedown', e => e.stopPropagation());
@@ -26,26 +32,46 @@ class Popup {
         this.container.setAttribute('src', chrome.extension.getURL('/fg/float.html'));
         this.container.style.width = '0px';
         this.container.style.height = '0px';
-        this.injected = null;
+        this.injectPromise = null;
+        this.isInjected = false;
     }
 
     inject(options) {
-        if (!this.injected) {
-            this.injected = new Promise((resolve, reject) => {
-                this.container.addEventListener('load', () => {
-                    this.invokeApi('setOptions', {
-                        general: {
-                            customPopupCss: options.general.customPopupCss
-                        }
-                    });
-                    resolve();
-                });
-                this.observeFullscreen();
-                this.onFullscreenChanged();
-            });
+        if (this.injectPromise === null) {
+            this.injectPromise = this.createInjectPromise(options);
+        }
+        return this.injectPromise;
+    }
+
+    async createInjectPromise(options) {
+        try {
+            const {frameId} = await this.frameIdPromise;
+            if (typeof frameId === 'number') {
+                this.frameId = frameId;
+            }
+        } catch (e) {
+            // NOP
         }
 
-        return this.injected;
+        return new Promise((resolve) => {
+            const parentFrameId = (typeof this.frameId === 'number' ? this.frameId : null);
+            this.container.addEventListener('load', () => {
+                this.invokeApi('popupNestedInitialize', {
+                    id: this.id,
+                    depth: this.depth,
+                    parentFrameId
+                });
+                this.invokeApi('setOptions', {
+                    general: {
+                        customPopupCss: options.general.customPopupCss
+                    }
+                });
+                resolve();
+            });
+            this.observeFullscreen();
+            this.onFullscreenChanged();
+            this.isInjected = true;
+        });
     }
 
     async show(elementRect, writingMode, options) {
@@ -77,6 +103,8 @@ class Popup {
         container.style.width = `${width}px`;
         container.style.height = `${height}px`;
         container.style.visibility = 'visible';
+
+        this.hideChildren();
     }
 
     static getPositionForHorizontalText(elementRect, width, height, maxWidth, maxHeight, optionsGeneral) {
@@ -178,12 +206,28 @@ class Popup {
     }
 
     hide() {
+        this.hideChildren();
+        this.hideContainer();
+        this.focusParent();
+    }
+
+    hideChildren() {
+        // recursively hides all children
+        if (this.child && !this.child.isContainerHidden()) {
+            this.child.hide();
+        }
+    }
+
+    hideContainer() {
         this.container.style.visibility = 'hidden';
-        this.container.blur();
+    }
+
+    isContainerHidden() {
+        return (this.container.style.visibility === 'hidden');
     }
 
     isVisible() {
-        return this.injected && this.container.style.visibility !== 'hidden';
+        return this.isInjected && this.container.style.visibility !== 'hidden';
     }
 
     setVisible(visible) {
@@ -194,19 +238,27 @@ class Popup {
         }
     }
 
-    containsPoint(point) {
-        if (!this.isVisible()) {
-            return false;
+    focusParent() {
+        if (this.parent && this.parent.container) {
+            // Chrome doesn't like focusing iframe without contentWindow.
+            this.parent.container.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();
         }
+    }
 
-        const rect = this.container.getBoundingClientRect();
-        const contained =
-            point.x >= rect.left &&
-            point.y >= rect.top &&
-            point.x < rect.right &&
-            point.y < rect.bottom;
-
-        return contained;
+    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 termsShow(elementRect, writingMode, definitions, options, context) {
@@ -220,7 +272,7 @@ class Popup {
     }
 
     clearAutoPlayTimer() {
-        if (this.injected) {
+        if (this.isInjected) {
             this.invokeApi('clearAutoPlayTimer');
         }
     }
diff --git a/ext/fg/js/source.js b/ext/fg/js/source.js
index e724488d..385b5001 100644
--- a/ext/fg/js/source.js
+++ b/ext/fg/js/source.js
@@ -232,6 +232,50 @@ class TextSourceRange {
         const writingMode = style.writingMode;
         return typeof writingMode === 'string' ? writingMode : 'horizontal-tb';
     }
+
+    static getNodesInRange(range) {
+        const end = range.endContainer;
+        const nodes = [];
+        for (let node = range.startContainer; node !== null; node = TextSourceRange.getNextNode(node)) {
+            nodes.push(node);
+            if (node === end) { break; }
+        }
+        return nodes;
+    }
+
+    static getNextNode(node) {
+        let next = node.firstChild;
+        if (next === null) {
+            while (true) {
+                next = node.nextSibling;
+                if (next !== null) { break; }
+
+                next = node.parentNode;
+                if (node === null) { break; }
+
+                node = next;
+            }
+        }
+        return next;
+    }
+
+    static anyNodeMatchesSelector(nodeList, selector) {
+        for (const node of nodeList) {
+            if (TextSourceRange.nodeMatchesSelector(node, selector)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    static nodeMatchesSelector(node, selector) {
+        for (; node !== null; node = node.parentNode) {
+            if (node.nodeType === Node.ELEMENT_NODE) {
+                return node.matches(selector);
+            }
+        }
+        return false;
+    }
 }
 
 
diff --git a/ext/fg/js/util.js b/ext/fg/js/util.js
index 7518beb5..dc99274e 100644
--- a/ext/fg/js/util.js
+++ b/ext/fg/js/util.js
@@ -24,9 +24,10 @@ function utilAsync(func) {
 }
 
 function utilInvoke(action, params={}) {
+    const data = {action, params};
     return new Promise((resolve, reject) => {
         try {
-            chrome.runtime.sendMessage({action, params}, (response) => {
+            chrome.runtime.sendMessage(data, (response) => {
                 utilCheckLastError(chrome.runtime.lastError);
                 if (response !== null && typeof response === 'object') {
                     if (response.error) {
@@ -35,7 +36,8 @@ function utilInvoke(action, params={}) {
                         resolve(response.result);
                     }
                 } else {
-                    reject(`Unexpected response of type ${typeof response}`);
+                    const message = response === null ? 'Unexpected null response' : `Unexpected response of type ${typeof response}`;
+                    reject(`${message} (${JSON.stringify(data)})`);
                 }
             });
         } catch (e) {
diff --git a/ext/manifest.json b/ext/manifest.json
index 62eed6ec..06d13dd1 100644
--- a/ext/manifest.json
+++ b/ext/manifest.json
@@ -21,9 +21,11 @@
             "mixed/js/extension.js",
             "fg/js/api.js",
             "fg/js/document.js",
+            "fg/js/frontend-api-receiver.js",
             "fg/js/popup.js",
             "fg/js/source.js",
             "fg/js/util.js",
+            "fg/js/popup-proxy-host.js",
             "fg/js/frontend.js"
         ],
         "css": ["fg/css/client.css"],