Merge branch 'master' into testing

13 files changed, 1254 insertions, 363 deletions

diff --git a/ext/mixed/js/api.js b/ext/mixed/js/api.js
index 0bc91759..5c17d50e 100644
--- a/ext/mixed/js/api.js
+++ b/ext/mixed/js/api.js
@@ -15,307 +15,341 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/* global
+ * CrossFrameAPI
+ */
+
+const api = (() => {
+    class API {
+        constructor() {
+            this._forwardLogsToBackendEnabled = false;
+            this._crossFrame = new CrossFrameAPI();
+        }
+
+        get crossFrame() {
+            return this._crossFrame;
+        }
+
+        prepare() {
+            this._crossFrame.prepare();
+        }
+
+        forwardLogsToBackend() {
+            if (this._forwardLogsToBackendEnabled) { return; }
+            this._forwardLogsToBackendEnabled = true;
+
+            yomichan.on('log', async ({error, level, context}) => {
+                try {
+                    await this.log(errorToJson(error), level, context);
+                } catch (e) {
+                    // NOP
+                }
+            });
+        }
+
+        // Invoke functions
+
+        optionsSchemaGet() {
+            return this._invoke('optionsSchemaGet');
+        }
+
+        optionsGet(optionsContext) {
+            return this._invoke('optionsGet', {optionsContext});
+        }
+
+        optionsGetFull() {
+            return this._invoke('optionsGetFull');
+        }
+
+        optionsSave(source) {
+            return this._invoke('optionsSave', {source});
+        }
+
+        termsFind(text, details, optionsContext) {
+            return this._invoke('termsFind', {text, details, optionsContext});
+        }
+
+        textParse(text, optionsContext) {
+            return this._invoke('textParse', {text, optionsContext});
+        }
+
+        kanjiFind(text, optionsContext) {
+            return this._invoke('kanjiFind', {text, optionsContext});
+        }
+
+        definitionAdd(definition, mode, context, details, optionsContext) {
+            return this._invoke('definitionAdd', {definition, mode, context, details, optionsContext});
+        }
+
+        definitionsAddable(definitions, modes, context, optionsContext) {
+            return this._invoke('definitionsAddable', {definitions, modes, context, optionsContext});
+        }
+
+        noteView(noteId) {
+            return this._invoke('noteView', {noteId});
+        }
+
+        templateRender(template, data) {
+            return this._invoke('templateRender', {data, template});
+        }
+
+        audioGetUri(definition, source, details) {
+            return this._invoke('audioGetUri', {definition, source, details});
+        }
+
+        commandExec(command, params) {
+            return this._invoke('commandExec', {command, params});
+        }
+
+        screenshotGet(options) {
+            return this._invoke('screenshotGet', {options});
+        }
+
+        sendMessageToFrame(frameId, action, params) {
+            return this._invoke('sendMessageToFrame', {frameId, action, params});
+        }
+
+        broadcastTab(action, params) {
+            return this._invoke('broadcastTab', {action, params});
+        }
+
+        frameInformationGet() {
+            return this._invoke('frameInformationGet');
+        }
+
+        injectStylesheet(type, value) {
+            return this._invoke('injectStylesheet', {type, value});
+        }
+
+        getStylesheetContent(url) {
+            return this._invoke('getStylesheetContent', {url});
+        }
+
+        getEnvironmentInfo() {
+            return this._invoke('getEnvironmentInfo');
+        }
+
+        clipboardGet() {
+            return this._invoke('clipboardGet');
+        }
 
-function apiOptionsSchemaGet() {
-    return _apiInvoke('optionsSchemaGet');
-}
+        getDisplayTemplatesHtml() {
+            return this._invoke('getDisplayTemplatesHtml');
+        }
+
+        getQueryParserTemplatesHtml() {
+            return this._invoke('getQueryParserTemplatesHtml');
+        }
+
+        getZoom() {
+            return this._invoke('getZoom');
+        }
+
+        getDefaultAnkiFieldTemplates() {
+            return this._invoke('getDefaultAnkiFieldTemplates');
+        }
+
+        getAnkiDeckNames() {
+            return this._invoke('getAnkiDeckNames');
+        }
+
+        getAnkiModelNames() {
+            return this._invoke('getAnkiModelNames');
+        }
+
+        getAnkiModelFieldNames(modelName) {
+            return this._invoke('getAnkiModelFieldNames', {modelName});
+        }
+
+        getDictionaryInfo() {
+            return this._invoke('getDictionaryInfo');
+        }
+
+        getDictionaryCounts(dictionaryNames, getTotal) {
+            return this._invoke('getDictionaryCounts', {dictionaryNames, getTotal});
+        }
 
-function apiOptionsGet(optionsContext) {
-    return _apiInvoke('optionsGet', {optionsContext});
-}
+        purgeDatabase() {
+            return this._invoke('purgeDatabase');
+        }
 
-function apiOptionsGetFull() {
-    return _apiInvoke('optionsGetFull');
-}
+        getMedia(targets) {
+            return this._invoke('getMedia', {targets});
+        }
+
+        log(error, level, context) {
+            return this._invoke('log', {error, level, context});
+        }
 
-function apiOptionsSave(source) {
-    return _apiInvoke('optionsSave', {source});
-}
+        logIndicatorClear() {
+            return this._invoke('logIndicatorClear');
+        }
 
-function apiTermsFind(text, details, optionsContext) {
-    return _apiInvoke('termsFind', {text, details, optionsContext});
-}
+        modifySettings(targets, source) {
+            return this._invoke('modifySettings', {targets, source});
+        }
 
-function apiTextParse(text, optionsContext) {
-    return _apiInvoke('textParse', {text, optionsContext});
-}
+        getSettings(targets) {
+            return this._invoke('getSettings', {targets});
+        }
 
-function apiKanjiFind(text, optionsContext) {
-    return _apiInvoke('kanjiFind', {text, optionsContext});
-}
+        setAllSettings(value, source) {
+            return this._invoke('setAllSettings', {value, source});
+        }
 
-function apiDefinitionAdd(definition, mode, context, details, optionsContext) {
-    return _apiInvoke('definitionAdd', {definition, mode, context, details, optionsContext});
-}
+        // Invoke functions with progress
 
-function apiDefinitionsAddable(definitions, modes, context, optionsContext) {
-    return _apiInvoke('definitionsAddable', {definitions, modes, context, optionsContext});
-}
+        importDictionaryArchive(archiveContent, details, onProgress) {
+            return this._invokeWithProgress('importDictionaryArchive', {archiveContent, details}, onProgress);
+        }
 
-function apiNoteView(noteId) {
-    return _apiInvoke('noteView', {noteId});
-}
+        deleteDictionary(dictionaryName, onProgress) {
+            return this._invokeWithProgress('deleteDictionary', {dictionaryName}, onProgress);
+        }
 
-function apiTemplateRender(template, data) {
-    return _apiInvoke('templateRender', {data, template});
-}
+        // Utilities
 
-function apiAudioGetUri(definition, source, details) {
-    return _apiInvoke('audioGetUri', {definition, source, details});
-}
+        _createActionPort(timeout=5000) {
+            return new Promise((resolve, reject) => {
+                let timer = null;
+                let portNameResolve;
+                let portNameReject;
+                const portNamePromise = new Promise((resolve2, reject2) => {
+                    portNameResolve = resolve2;
+                    portNameReject = reject2;
+                });
 
-function apiCommandExec(command, params) {
-    return _apiInvoke('commandExec', {command, params});
-}
-
-function apiScreenshotGet(options) {
-    return _apiInvoke('screenshotGet', {options});
-}
-
-function apiSendMessageToFrame(frameId, action, params) {
-    return _apiInvoke('sendMessageToFrame', {frameId, action, params});
-}
-
-function apiBroadcastTab(action, params) {
-    return _apiInvoke('broadcastTab', {action, params});
-}
-
-function apiFrameInformationGet() {
-    return _apiInvoke('frameInformationGet');
-}
-
-function apiInjectStylesheet(type, value) {
-    return _apiInvoke('injectStylesheet', {type, value});
-}
-
-function apiGetEnvironmentInfo() {
-    return _apiInvoke('getEnvironmentInfo');
-}
-
-function apiClipboardGet() {
-    return _apiInvoke('clipboardGet');
-}
-
-function apiGetDisplayTemplatesHtml() {
-    return _apiInvoke('getDisplayTemplatesHtml');
-}
-
-function apiGetQueryParserTemplatesHtml() {
-    return _apiInvoke('getQueryParserTemplatesHtml');
-}
-
-function apiGetZoom() {
-    return _apiInvoke('getZoom');
-}
-
-function apiGetDefaultAnkiFieldTemplates() {
-    return _apiInvoke('getDefaultAnkiFieldTemplates');
-}
-
-function apiGetAnkiDeckNames() {
-    return _apiInvoke('getAnkiDeckNames');
-}
-
-function apiGetAnkiModelNames() {
-    return _apiInvoke('getAnkiModelNames');
-}
-
-function apiGetAnkiModelFieldNames(modelName) {
-    return _apiInvoke('getAnkiModelFieldNames', {modelName});
-}
-
-function apiGetDictionaryInfo() {
-    return _apiInvoke('getDictionaryInfo');
-}
-
-function apiGetDictionaryCounts(dictionaryNames, getTotal) {
-    return _apiInvoke('getDictionaryCounts', {dictionaryNames, getTotal});
-}
-
-function apiPurgeDatabase() {
-    return _apiInvoke('purgeDatabase');
-}
-
-function apiGetMedia(targets) {
-    return _apiInvoke('getMedia', {targets});
-}
-
-function apiLog(error, level, context) {
-    return _apiInvoke('log', {error, level, context});
-}
-
-function apiLogIndicatorClear() {
-    return _apiInvoke('logIndicatorClear');
-}
-
-function apiImportDictionaryArchive(archiveContent, details, onProgress) {
-    return _apiInvokeWithProgress('importDictionaryArchive', {archiveContent, details}, onProgress);
-}
-
-function apiDeleteDictionary(dictionaryName, onProgress) {
-    return _apiInvokeWithProgress('deleteDictionary', {dictionaryName}, onProgress);
-}
-
-function apiModifySettings(targets, source) {
-    return _apiInvoke('modifySettings', {targets, source});
-}
-
-function _apiCreateActionPort(timeout=5000) {
-    return new Promise((resolve, reject) => {
-        let timer = null;
-        let portNameResolve;
-        let portNameReject;
-        const portNamePromise = new Promise((resolve2, reject2) => {
-            portNameResolve = resolve2;
-            portNameReject = reject2;
-        });
-
-        const onConnect = async (port) => {
-            try {
-                const portName = await portNamePromise;
-                if (port.name !== portName || timer === null) { return; }
-            } catch (e) {
-                return;
-            }
-
-            clearTimeout(timer);
-            timer = null;
-
-            chrome.runtime.onConnect.removeListener(onConnect);
-            resolve(port);
-        };
-
-        const onError = (e) => {
-            if (timer !== null) {
-                clearTimeout(timer);
-                timer = null;
-            }
-            chrome.runtime.onConnect.removeListener(onConnect);
-            portNameReject(e);
-            reject(e);
-        };
-
-        timer = setTimeout(() => onError(new Error('Timeout')), timeout);
-
-        chrome.runtime.onConnect.addListener(onConnect);
-        _apiInvoke('createActionPort').then(portNameResolve, onError);
-    });
-}
-
-function _apiInvokeWithProgress(action, params, onProgress, timeout=5000) {
-    return new Promise((resolve, reject) => {
-        let timer = null;
-        let port = null;
-
-        if (typeof onProgress !== 'function') {
-            onProgress = () => {};
-        }
-
-        const onMessage = (message) => {
-            switch (message.type) {
-                case 'ack':
+                const onConnect = async (port) => {
+                    try {
+                        const portName = await portNamePromise;
+                        if (port.name !== portName || timer === null) { return; }
+                    } catch (e) {
+                        return;
+                    }
+
+                    clearTimeout(timer);
+                    timer = null;
+
+                    chrome.runtime.onConnect.removeListener(onConnect);
+                    resolve(port);
+                };
+
+                const onError = (e) => {
                     if (timer !== null) {
                         clearTimeout(timer);
                         timer = null;
                     }
-                    break;
-                case 'progress':
-                    try {
-                        onProgress(...message.data);
-                    } catch (e) {
-                        // NOP
+                    chrome.runtime.onConnect.removeListener(onConnect);
+                    portNameReject(e);
+                    reject(e);
+                };
+
+                timer = setTimeout(() => onError(new Error('Timeout')), timeout);
+
+                chrome.runtime.onConnect.addListener(onConnect);
+                this._invoke('createActionPort').then(portNameResolve, onError);
+            });
+        }
+
+        _invokeWithProgress(action, params, onProgress, timeout=5000) {
+            return new Promise((resolve, reject) => {
+                let port = null;
+
+                if (typeof onProgress !== 'function') {
+                    onProgress = () => {};
+                }
+
+                const onMessage = (message) => {
+                    switch (message.type) {
+                        case 'progress':
+                            try {
+                                onProgress(...message.data);
+                            } catch (e) {
+                                // NOP
+                            }
+                            break;
+                        case 'complete':
+                            cleanup();
+                            resolve(message.data);
+                            break;
+                        case 'error':
+                            cleanup();
+                            reject(jsonToError(message.data));
+                            break;
                     }
-                    break;
-                case 'complete':
-                    cleanup();
-                    resolve(message.data);
-                    break;
-                case 'error':
+                };
+
+                const onDisconnect = () => {
                     cleanup();
-                    reject(jsonToError(message.data));
-                    break;
-            }
-        };
-
-        const onDisconnect = () => {
-            cleanup();
-            reject(new Error('Disconnected'));
-        };
-
-        const cleanup = () => {
-            if (timer !== null) {
-                clearTimeout(timer);
-                timer = null;
-            }
-            if (port !== null) {
-                port.onMessage.removeListener(onMessage);
-                port.onDisconnect.removeListener(onDisconnect);
-                port.disconnect();
-                port = null;
-            }
-            onProgress = null;
-        };
-
-        timer = setTimeout(() => {
-            cleanup();
-            reject(new Error('Timeout'));
-        }, timeout);
-
-        (async () => {
-            try {
-                port = await _apiCreateActionPort(timeout);
-                port.onMessage.addListener(onMessage);
-                port.onDisconnect.addListener(onDisconnect);
-                port.postMessage({action, params});
-            } catch (e) {
-                cleanup();
-                reject(e);
-            } finally {
-                action = null;
-                params = null;
-            }
-        })();
-    });
-}
-
-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);
+                    reject(new Error('Disconnected'));
+                };
+
+                const cleanup = () => {
+                    if (port !== null) {
+                        port.onMessage.removeListener(onMessage);
+                        port.onDisconnect.removeListener(onDisconnect);
+                        port.disconnect();
+                        port = null;
+                    }
+                    onProgress = null;
+                };
+
+                (async () => {
+                    try {
+                        port = await this._createActionPort(timeout);
+                        port.onMessage.addListener(onMessage);
+                        port.onDisconnect.addListener(onDisconnect);
+
+                        // Chrome has a maximum message size that can be sent, so longer messages must be fragmented.
+                        const messageString = JSON.stringify({action, params});
+                        const fragmentSize = 1e7; // 10 MB
+                        for (let i = 0, ii = messageString.length; i < ii; i += fragmentSize) {
+                            const data = messageString.substring(i, i + fragmentSize);
+                            port.postMessage({action: 'fragment', data});
+                        }
+                        port.postMessage({action: 'invoke'});
+                    } catch (e) {
+                        cleanup();
+                        reject(e);
+                    } finally {
+                        action = null;
+                        params = null;
                     }
-                } else {
-                    const message = response === null ? 'Unexpected null response' : `Unexpected response of type ${typeof response}`;
-                    reject(new Error(`${message} (${JSON.stringify(data)})`));
+                })();
+            });
+        }
+
+        _invoke(action, params={}) {
+            const data = {action, params};
+            return new Promise((resolve, reject) => {
+                try {
+                    chrome.runtime.sendMessage(data, (response) => {
+                        this._checkLastError(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) {
+                    reject(e);
+                    yomichan.triggerOrphaned(e);
                 }
             });
-        } catch (e) {
-            reject(e);
-            yomichan.triggerOrphaned(e);
-        }
-    });
-}
-
-function _apiCheckLastError() {
-    // NOP
-}
-
-let _apiForwardLogsToBackendEnabled = false;
-function apiForwardLogsToBackend() {
-    if (_apiForwardLogsToBackendEnabled) { return; }
-    _apiForwardLogsToBackendEnabled = true;
-
-    yomichan.on('log', async ({error, level, context}) => {
-        try {
-            await apiLog(errorToJson(error), level, context);
-        } catch (e) {
+        }
+
+        _checkLastError() {
             // NOP
         }
-    });
-}
+    }
+
+    // eslint-disable-next-line no-shadow
+    const api = new API();
+    api.prepare();
+    return api;
+})();
diff --git a/ext/mixed/js/audio-system.js b/ext/mixed/js/audio-system.js
index fdfb0b10..c590b909 100644
--- a/ext/mixed/js/audio-system.js
+++ b/ext/mixed/js/audio-system.js
@@ -169,22 +169,22 @@ class AudioSystem {
         });
     }
 
-    _createAudioBinaryFromUrl(url) {
-        return new Promise((resolve, reject) => {
-            const xhr = new XMLHttpRequest();
-            xhr.responseType = 'arraybuffer';
-            xhr.addEventListener('load', async () => {
-                const arrayBuffer = xhr.response;
-                if (!await this._isAudioBinaryValid(arrayBuffer)) {
-                    reject(new Error('Could not retrieve audio'));
-                } else {
-                    resolve(arrayBuffer);
-                }
-            });
-            xhr.addEventListener('error', () => reject(new Error('Failed to connect')));
-            xhr.open('GET', url);
-            xhr.send();
+    async _createAudioBinaryFromUrl(url) {
+        const response = await fetch(url, {
+            method: 'GET',
+            mode: 'no-cors',
+            cache: 'default',
+            credentials: 'omit',
+            redirect: 'follow',
+            referrerPolicy: 'no-referrer'
         });
+        const arrayBuffer = await response.arrayBuffer();
+
+        if (!await this._isAudioBinaryValid(arrayBuffer)) {
+            throw new Error('Could not retrieve audio');
+        }
+
+        return arrayBuffer;
     }
 
     _isAudioValid(audio) {
diff --git a/ext/mixed/js/comm.js b/ext/mixed/js/comm.js
new file mode 100644
index 00000000..7787616e
--- /dev/null
+++ b/ext/mixed/js/comm.js
@@ -0,0 +1,282 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ */
+
+class CrossFrameAPIPort extends EventDispatcher {
+    constructor(otherFrameId, port, messageHandlers) {
+        super();
+        this._otherFrameId = otherFrameId;
+        this._port = port;
+        this._messageHandlers = messageHandlers;
+        this._activeInvocations = new Map();
+        this._invocationId = 0;
+        this._eventListeners = new EventListenerCollection();
+    }
+
+    get otherFrameId() {
+        return this._otherFrameId;
+    }
+
+    prepare() {
+        this._eventListeners.addListener(this._port.onDisconnect, this._onDisconnect.bind(this));
+        this._eventListeners.addListener(this._port.onMessage, this._onMessage.bind(this));
+    }
+
+    invoke(action, params, ackTimeout, responseTimeout) {
+        return new Promise((resolve, reject) => {
+            if (this._port === null) {
+                reject(new Error('Port is disconnected'));
+                return;
+            }
+
+            const id = this._invocationId++;
+            const invocation = {id, resolve, reject, responseTimeout, ack: false, timer: null};
+            this._activeInvocations.set(id, invocation);
+
+            if (ackTimeout !== null) {
+                try {
+                    invocation.timer = setTimeout(() => this._onError(id, new Error('Timeout (ack)')), ackTimeout);
+                } catch (e) {
+                    this._onError(id, new Error('Failed to set timeout'));
+                    return;
+                }
+            }
+
+            try {
+                this._port.postMessage({type: 'invoke', id, data: {action, params}});
+            } catch (e) {
+                this._onError(id, e);
+            }
+        });
+    }
+
+    disconnect() {
+        this._onDisconnect();
+    }
+
+    // Private
+
+    _onDisconnect() {
+        if (this._port === null) { return; }
+        this._eventListeners.removeAllEventListeners();
+        this._port = null;
+        for (const id of this._activeInvocations.keys()) {
+            this._onError(id, new Error('Disconnected'));
+        }
+        this.trigger('disconnect', this);
+    }
+
+    _onMessage({type, id, data}) {
+        switch (type) {
+            case 'invoke':
+                this._onInvoke(id, data);
+                break;
+            case 'ack':
+                this._onAck(id);
+                break;
+            case 'result':
+                this._onResult(id, data);
+                break;
+        }
+    }
+
+    // Response handlers
+
+    _onAck(id) {
+        const invocation = this._activeInvocations.get(id);
+        if (typeof invocation === 'undefined') {
+            yomichan.logWarning(new Error(`Request ${id} not found for ack`));
+            return;
+        }
+
+        if (invocation.ack) {
+            this._onError(id, new Error(`Request ${id} already ack'd`));
+            return;
+        }
+
+        invocation.ack = true;
+
+        if (invocation.timer !== null) {
+            clearTimeout(invocation.timer);
+            invocation.timer = null;
+        }
+
+        const responseTimeout = invocation.responseTimeout;
+        if (responseTimeout !== null) {
+            try {
+                invocation.timer = setTimeout(() => this._onError(id, new Error('Timeout (response)')), responseTimeout);
+            } catch (e) {
+                this._onError(id, new Error('Failed to set timeout'));
+            }
+        }
+    }
+
+    _onResult(id, data) {
+        const invocation = this._activeInvocations.get(id);
+        if (typeof invocation === 'undefined') {
+            yomichan.logWarning(new Error(`Request ${id} not found`));
+            return;
+        }
+
+        if (!invocation.ack) {
+            this._onError(id, new Error(`Request ${id} not ack'd`));
+            return;
+        }
+
+        this._activeInvocations.delete(id);
+
+        if (invocation.timer !== null) {
+            clearTimeout(invocation.timer);
+            invocation.timer = null;
+        }
+
+        const error = data.error;
+        if (typeof error !== 'undefined') {
+            invocation.reject(jsonToError(error));
+        } else {
+            invocation.resolve(data.result);
+        }
+    }
+
+    _onError(id, error) {
+        const invocation = this._activeInvocations.get(id);
+        if (typeof invocation === 'undefined') { return; }
+
+        this._activeInvocations.delete(id);
+        if (invocation.timer !== null) {
+            clearTimeout(invocation.timer);
+            invocation.timer = null;
+        }
+        invocation.reject(error);
+    }
+
+    // Invocation
+
+    _onInvoke(id, {action, params}) {
+        const messageHandler = this._messageHandlers.get(action);
+        if (typeof messageHandler === 'undefined') {
+            this._sendError(id, new Error(`Unknown action: ${action}`));
+            return;
+        }
+
+        const {handler, async} = messageHandler;
+
+        this._sendAck(id);
+        if (async) {
+            this._invokeHandlerAsync(id, handler, params);
+        } else {
+            this._invokeHandler(id, handler, params);
+        }
+    }
+
+    _invokeHandler(id, handler, params) {
+        try {
+            const result = handler(params);
+            this._sendResult(id, result);
+        } catch (error) {
+            this._sendError(id, error);
+        }
+    }
+
+    async _invokeHandlerAsync(id, handler, params) {
+        try {
+            const result = await handler(params);
+            this._sendResult(id, result);
+        } catch (error) {
+            this._sendError(id, error);
+        }
+    }
+
+    _sendResponse(data) {
+        if (this._port === null) { return; }
+        try {
+            this._port.postMessage(data);
+        } catch (e) {
+            // NOP
+        }
+    }
+
+    _sendAck(id) {
+        this._sendResponse({type: 'ack', id});
+    }
+
+    _sendResult(id, result) {
+        this._sendResponse({type: 'result', id, data: {result}});
+    }
+
+    _sendError(id, error) {
+        this._sendResponse({type: 'result', id, data: {error: errorToJson(error)}});
+    }
+}
+
+class CrossFrameAPI {
+    constructor() {
+        this._ackTimeout = 3000; // 3 seconds
+        this._responseTimeout = 10000; // 10 seconds
+        this._commPorts = new Map();
+        this._messageHandlers = new Map();
+        this._onDisconnectBind = this._onDisconnect.bind(this);
+    }
+
+    prepare() {
+        chrome.runtime.onConnect.addListener(this._onConnect.bind(this));
+    }
+
+    async invoke(targetFrameId, action, params={}) {
+        const commPort = this._getOrCreateCommPort(targetFrameId);
+        return await commPort.invoke(action, params, this._ackTimeout, this._responseTimeout);
+    }
+
+    registerHandlers(messageHandlers) {
+        for (const [key, value] of messageHandlers) {
+            if (this._messageHandlers.has(key)) {
+                throw new Error(`Handler ${key} is already registered`);
+            }
+            this._messageHandlers.set(key, value);
+        }
+    }
+
+    _onConnect(port) {
+        const match = /^cross-frame-communication-port-(\d+)$/.exec(`${port.name}`);
+        if (match === null) { return; }
+
+        const otherFrameId = parseInt(match[1], 10);
+        this._setupCommPort(otherFrameId, port);
+    }
+
+    _onDisconnect(commPort) {
+        commPort.off('disconnect', this._onDisconnectBind);
+        this._commPorts.delete(commPort.otherFrameId);
+    }
+
+    _getOrCreateCommPort(otherFrameId) {
+        const commPort = this._commPorts.get(otherFrameId);
+        return (typeof commPort !== 'undefined' ? commPort : this._createCommPort(otherFrameId));
+    }
+
+    _createCommPort(otherFrameId) {
+        const port = chrome.runtime.connect(null, {name: `background-cross-frame-communication-port-${otherFrameId}`});
+        return this._setupCommPort(otherFrameId, port);
+    }
+
+    _setupCommPort(otherFrameId, port) {
+        const commPort = new CrossFrameAPIPort(otherFrameId, port, this._messageHandlers);
+        this._commPorts.set(otherFrameId, commPort);
+        commPort.prepare();
+        commPort.on('disconnect', this._onDisconnectBind);
+        return commPort;
+    }
+}
diff --git a/ext/mixed/js/core.js b/ext/mixed/js/core.js
index 589425f2..bf877e72 100644
--- a/ext/mixed/js/core.js
+++ b/ext/mixed/js/core.js
@@ -164,7 +164,10 @@ function getSetDifference(set1, set2) {
 
 function promiseTimeout(delay, resolveValue) {
     if (delay <= 0) {
-        return Promise.resolve(resolveValue);
+        const promise = Promise.resolve(resolveValue);
+        promise.resolve = () => {}; // NOP
+        promise.reject = () => {}; // NOP
+        return promise;
     }
 
     let timer = null;
@@ -174,7 +177,7 @@ function promiseTimeout(delay, resolveValue) {
     const complete = (callback, value) => {
         if (callback === null) { return; }
         if (timer !== null) {
-            window.clearTimeout(timer);
+            clearTimeout(timer);
             timer = null;
         }
         promiseResolve = null;
@@ -189,7 +192,7 @@ function promiseTimeout(delay, resolveValue) {
         promiseResolve = resolve2;
         promiseReject = reject2;
     });
-    timer = window.setTimeout(() => {
+    timer = setTimeout(() => {
         timer = null;
         resolve(resolveValue);
     }, delay);
@@ -255,15 +258,37 @@ class EventListenerCollection {
         return this._eventListeners.length;
     }
 
-    addEventListener(node, type, listener, options) {
-        node.addEventListener(type, listener, options);
-        this._eventListeners.push([node, type, listener, options]);
+    addEventListener(object, ...args) {
+        object.addEventListener(...args);
+        this._eventListeners.push(['removeEventListener', object, ...args]);
+    }
+
+    addListener(object, ...args) {
+        object.addListener(...args);
+        this._eventListeners.push(['removeListener', object, ...args]);
+    }
+
+    on(object, ...args) {
+        object.on(...args);
+        this._eventListeners.push(['off', object, ...args]);
     }
 
     removeAllEventListeners() {
         if (this._eventListeners.length === 0) { return; }
-        for (const [node, type, listener, options] of this._eventListeners) {
-            node.removeEventListener(type, listener, options);
+        for (const [removeFunctionName, object, ...args] of this._eventListeners) {
+            switch (removeFunctionName) {
+                case 'removeEventListener':
+                    object.removeEventListener(...args);
+                    break;
+                case 'removeListener':
+                    object.removeListener(...args);
+                    break;
+                case 'off':
+                    object.off(...args);
+                    break;
+                default:
+                    throw new Error(`Unknown remove function: ${removeFunctionName}`);
+            }
         }
         this._eventListeners = [];
     }
@@ -306,7 +331,7 @@ const yomichan = (() => {
 
         generateId(length) {
             const array = new Uint8Array(length);
-            window.crypto.getRandomValues(array);
+            crypto.getRandomValues(array);
             let id = '';
             for (const value of array) {
                 id += value.toString(16).padStart(2, '0');
@@ -339,7 +364,7 @@ const yomichan = (() => {
                 const runtimeMessageCallback = ({action, params}, sender, sendResponse) => {
                     let timeoutId = null;
                     if (timeout !== null) {
-                        timeoutId = window.setTimeout(() => {
+                        timeoutId = setTimeout(() => {
                             timeoutId = null;
                             eventHandler.removeListener(runtimeMessageCallback);
                             reject(new Error(`Listener timed out in ${timeout} ms`));
@@ -348,7 +373,7 @@ const yomichan = (() => {
 
                     const cleanupResolve = (value) => {
                         if (timeoutId !== null) {
-                            window.clearTimeout(timeoutId);
+                            clearTimeout(timeoutId);
                             timeoutId = null;
                         }
                         eventHandler.removeListener(runtimeMessageCallback);
@@ -428,10 +453,12 @@ const yomichan = (() => {
 
         // Private
 
+        _getUrl() {
+            return (typeof window === 'object' && window !== null ? window.location.href : '');
+        }
+
         _getLogContext() {
-            return {
-                url: window.location.href
-            };
+            return {url: this._getUrl()};
         }
 
         _onMessage({action, params}, sender, callback) {
@@ -444,7 +471,7 @@ const yomichan = (() => {
         }
 
         _onMessageGetUrl() {
-            return {url: window.location.href};
+            return {url: this._getUrl()};
         }
 
         _onMessageOptionsUpdated({source}) {
diff --git a/ext/mixed/js/display-generator.js b/ext/mixed/js/display-generator.js
index a2b2b139..3f3a155e 100644
--- a/ext/mixed/js/display-generator.js
+++ b/ext/mixed/js/display-generator.js
@@ -17,7 +17,7 @@
 
 /* global
  * TemplateHandler
- * apiGetDisplayTemplatesHtml
+ * api
  * jp
  */
 
@@ -29,7 +29,7 @@ class DisplayGenerator {
     }
 
     async prepare() {
-        const html = await apiGetDisplayTemplatesHtml();
+        const html = await api.getDisplayTemplatesHtml();
         this._templateHandler = new TemplateHandler(html);
     }
 
diff --git a/ext/mixed/js/display.js b/ext/mixed/js/display.js
index 2e59b4ff..1d699706 100644
--- a/ext/mixed/js/display.js
+++ b/ext/mixed/js/display.js
@@ -22,15 +22,7 @@
  * DisplayGenerator
  * MediaLoader
  * WindowScroll
- * apiAudioGetUri
- * apiBroadcastTab
- * apiDefinitionAdd
- * apiDefinitionsAddable
- * apiKanjiFind
- * apiNoteView
- * apiOptionsGet
- * apiScreenshotGet
- * apiTermsFind
+ * api
  * docRangeFromPoint
  * docSentenceExtract
  */
@@ -49,7 +41,7 @@ class Display {
         this.audioSystem = new AudioSystem({
             audioUriBuilder: {
                 getUri: async (definition, source, details) => {
-                    return await apiAudioGetUri(definition, source, details);
+                    return await api.audioGetUri(definition, source, details);
                 }
             },
             useCache: true
@@ -212,7 +204,7 @@ class Display {
                 url: this.context.get('url')
             };
 
-            const definitions = await apiKanjiFind(link.textContent, this.getOptionsContext());
+            const definitions = await api.kanjiFind(link.textContent, this.getOptionsContext());
             this.setContent('kanji', {definitions, context});
         } catch (error) {
             this.onError(error);
@@ -244,7 +236,9 @@ class Display {
             const {textSource, definitions} = termLookupResults;
 
             const scannedElement = e.target;
-            const sentence = docSentenceExtract(textSource, this.options.anki.sentenceExt);
+            const sentenceExtent = this.options.anki.sentenceExt;
+            const layoutAwareScan = this.options.scanning.layoutAwareScan;
+            const sentence = docSentenceExtract(textSource, sentenceExtent, layoutAwareScan);
 
             this.context.update({
                 index: this.entryIndexFind(scannedElement),
@@ -281,21 +275,22 @@ class Display {
         try {
             e.preventDefault();
 
-            const textSource = docRangeFromPoint(e.clientX, e.clientY, this.options.scanning.deepDomScan);
+            const {length: scanLength, deepDomScan: deepScan, layoutAwareScan} = this.options.scanning;
+            const textSource = docRangeFromPoint(e.clientX, e.clientY, deepScan);
             if (textSource === null) {
                 return false;
             }
 
             let definitions, length;
             try {
-                textSource.setEndOffset(this.options.scanning.length);
+                textSource.setEndOffset(scanLength, layoutAwareScan);
 
-                ({definitions, length} = await apiTermsFind(textSource.text(), {}, this.getOptionsContext()));
+                ({definitions, length} = await api.termsFind(textSource.text(), {}, this.getOptionsContext()));
                 if (definitions.length === 0) {
                     return false;
                 }
 
-                textSource.setEndOffset(length);
+                textSource.setEndOffset(length, layoutAwareScan);
             } finally {
                 textSource.cleanup();
             }
@@ -334,7 +329,7 @@ class Display {
     onNoteView(e) {
         e.preventDefault();
         const link = e.currentTarget;
-        apiNoteView(link.dataset.noteId);
+        api.noteView(link.dataset.noteId);
     }
 
     onKeyDown(e) {
@@ -379,7 +374,7 @@ class Display {
     }
 
     async updateOptions() {
-        this.options = await apiOptionsGet(this.getOptionsContext());
+        this.options = await api.optionsGet(this.getOptionsContext());
         this.updateDocumentOptions(this.options);
         this.updateTheme(this.options.general.popupTheme);
         this.setCustomCss(this.options.general.customPopupCss);
@@ -746,7 +741,7 @@ class Display {
     noteTryView() {
         const button = this.viewerButtonFind(this.index);
         if (button !== null && !button.classList.contains('disabled')) {
-            apiNoteView(button.dataset.noteId);
+            api.noteView(button.dataset.noteId);
         }
     }
 
@@ -763,7 +758,7 @@ class Display {
             }
 
             const context = await this._getNoteContext();
-            const noteId = await apiDefinitionAdd(definition, mode, context, details, this.getOptionsContext());
+            const noteId = await api.definitionAdd(definition, mode, context, details, this.getOptionsContext());
             if (noteId) {
                 const index = this.definitions.indexOf(definition);
                 const adderButton = this.adderButtonFind(index, mode);
@@ -815,9 +810,10 @@ class Display {
 
             this._stopPlayingAudio();
 
+            const volume = Math.max(0.0, Math.min(1.0, this.options.audio.volume / 100.0));
             this.audioPlaying = audio;
             audio.currentTime = 0;
-            audio.volume = this.options.audio.volume / 100.0;
+            audio.volume = Number.isFinite(volume) ? volume : 1.0;
             const playPromise = audio.play();
             if (typeof playPromise !== 'undefined') {
                 try {
@@ -857,7 +853,7 @@ class Display {
             await promiseTimeout(1); // Wait for popup to be hidden.
 
             const {format, quality} = this.options.anki.screenshot;
-            const dataUrl = await apiScreenshotGet({format, quality});
+            const dataUrl = await api.screenshotGet({format, quality});
             if (!dataUrl || dataUrl.error) { return; }
 
             return {dataUrl, format};
@@ -871,7 +867,7 @@ class Display {
     }
 
     setPopupVisibleOverride(visible) {
-        return apiBroadcastTab('popupSetVisibleOverride', {visible});
+        return api.broadcastTab('popupSetVisibleOverride', {visible});
     }
 
     setSpinnerVisible(visible) {
@@ -933,7 +929,7 @@ class Display {
     async getDefinitionsAddable(definitions, modes) {
         try {
             const context = await this._getNoteContext();
-            return await apiDefinitionsAddable(definitions, modes, context, this.getOptionsContext());
+            return await api.definitionsAddable(definitions, modes, context, this.getOptionsContext());
         } catch (e) {
             return [];
         }
diff --git a/ext/mixed/js/dom-data-binder.js b/ext/mixed/js/dom-data-binder.js
new file mode 100644
index 00000000..d46e8087
--- /dev/null
+++ b/ext/mixed/js/dom-data-binder.js
@@ -0,0 +1,349 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * TaskAccumulator
+ */
+
+class DOMDataBinder {
+    constructor({selector, ignoreSelectors=[], createElementMetadata, compareElementMetadata, getValues, setValues, onError=null}) {
+        this._selector = selector;
+        this._ignoreSelectors = ignoreSelectors;
+        this._createElementMetadata = createElementMetadata;
+        this._compareElementMetadata = compareElementMetadata;
+        this._getValues = getValues;
+        this._setValues = setValues;
+        this._onError = onError;
+        this._updateTasks = new TaskAccumulator(this._onBulkUpdate.bind(this));
+        this._assignTasks = new TaskAccumulator(this._onBulkAssign.bind(this));
+        this._mutationObserver = new MutationObserver(this._onMutation.bind(this));
+        this._observingElement = null;
+        this._elementMap = new Map(); // Map([element => observer]...)
+        this._elementAncestorMap = new Map(); // Map([element => Set([observer]...))
+    }
+
+    observe(element) {
+        if (this._isObserving) { return; }
+
+        this._observingElement = element;
+        this._mutationObserver.observe(element, {
+            attributes: true,
+            attributeOldValue: true,
+            childList: true,
+            subtree: true
+        });
+        this._onMutation([{
+            type: 'childList',
+            target: element.parentNode,
+            addedNodes: [element],
+            removedNodes: []
+        }]);
+    }
+
+    disconnect() {
+        if (!this._isObserving) { return; }
+
+        this._mutationObserver.disconnect();
+        this._observingElement = null;
+
+        for (const observer of this._elementMap.values()) {
+            this._removeObserver(observer);
+        }
+    }
+
+    async refresh() {
+        await this._updateTasks.enqueue(null, {all: true});
+    }
+
+    // Private
+
+    _onMutation(mutationList) {
+        for (const mutation of mutationList) {
+            switch (mutation.type) {
+                case 'childList':
+                    this._onChildListMutation(mutation);
+                    break;
+                case 'attributes':
+                    this._onAttributeMutation(mutation);
+                    break;
+            }
+        }
+    }
+
+    _onChildListMutation({addedNodes, removedNodes, target}) {
+        const selector = this._selector;
+        const ELEMENT_NODE = Node.ELEMENT_NODE;
+
+        for (const node of removedNodes) {
+            const observers = this._elementAncestorMap.get(node);
+            if (typeof observers === 'undefined') { continue; }
+            for (const observer of observers) {
+                this._removeObserver(observer);
+            }
+        }
+
+        for (const node of addedNodes) {
+            if (node.nodeType !== ELEMENT_NODE) { continue; }
+            if (node.matches(selector)) {
+                this._createObserver(node);
+            }
+            for (const childNode of node.querySelectorAll(selector)) {
+                this._createObserver(childNode);
+            }
+        }
+
+        if (addedNodes.length !== 0 || addedNodes.length !== 0) {
+            const observer = this._elementMap.get(target);
+            if (typeof observer !== 'undefined' && observer.hasValue) {
+                this._setElementValue(observer.element, observer.value);
+            }
+        }
+    }
+
+    _onAttributeMutation({target}) {
+        const selector = this._selector;
+        const observers = this._elementAncestorMap.get(target);
+        if (typeof observers !== 'undefined') {
+            for (const observer of observers) {
+                const element = observer.element;
+                if (
+                    !element.matches(selector) ||
+                    this._shouldIgnoreElement(element) ||
+                    this._isObserverStale(observer)
+                ) {
+                    this._removeObserver(observer);
+                }
+            }
+        }
+
+        if (target.matches(selector)) {
+            this._createObserver(target);
+        }
+    }
+
+    async _onBulkUpdate(tasks) {
+        let all = false;
+        const targets = [];
+        for (const [observer, task] of tasks) {
+            if (observer === null) {
+                if (task.data.all) {
+                    all = true;
+                    break;
+                }
+            } else {
+                targets.push([observer, task]);
+            }
+        }
+        if (all) {
+            targets.length = 0;
+            for (const observer of this._elementMap.values()) {
+                targets.push([observer, null]);
+            }
+        }
+
+        const args = targets.map(([observer]) => ({
+            element: observer.element,
+            metadata: observer.metadata
+        }));
+        const responses = await this._getValues(args);
+        this._applyValues(targets, responses, true);
+    }
+
+    async _onBulkAssign(tasks) {
+        const targets = tasks;
+        const args = targets.map(([observer, task]) => ({
+            element: observer.element,
+            metadata: observer.metadata,
+            value: task.data.value
+        }));
+        const responses = await this._setValues(args);
+        this._applyValues(targets, responses, false);
+    }
+
+    _onElementChange(observer) {
+        const value = this._getElementValue(observer.element);
+        observer.value = value;
+        observer.hasValue = true;
+        this._assignTasks.enqueue(observer, {value});
+    }
+
+    _applyValues(targets, response, ignoreStale) {
+        if (!Array.isArray(response)) { return; }
+
+        for (let i = 0, ii = targets.length; i < ii; ++i) {
+            const [observer, task] = targets[i];
+            const {error, result} = response[i];
+            const stale = (task !== null && task.stale);
+
+            if (error) {
+                if (typeof this._onError === 'function') {
+                    this._onError(error, stale, observer.element, observer.metadata);
+                }
+                continue;
+            }
+
+            if (stale && !ignoreStale) { continue; }
+
+            observer.value = result;
+            observer.hasValue = true;
+            this._setElementValue(observer.element, result);
+        }
+    }
+
+    _createObserver(element) {
+        if (this._elementMap.has(element) || this._shouldIgnoreElement(element)) { return; }
+
+        const metadata = this._createElementMetadata(element);
+        const nodeName = element.nodeName.toUpperCase();
+        const ancestors = this._getAncestors(element);
+        const observer = {
+            element,
+            ancestors,
+            type: (nodeName === 'INPUT' ? element.type : null),
+            value: null,
+            hasValue: false,
+            onChange: null,
+            metadata
+        };
+        observer.onChange = this._onElementChange.bind(this, observer);
+        this._elementMap.set(element, observer);
+
+        element.addEventListener('change', observer.onChange, false);
+
+        for (const ancestor of ancestors) {
+            let observers = this._elementAncestorMap.get(ancestor);
+            if (typeof observers === 'undefined') {
+                observers = new Set();
+                this._elementAncestorMap.set(ancestor, observers);
+            }
+            observers.add(observer);
+        }
+
+        this._updateTasks.enqueue(observer);
+    }
+
+    _removeObserver(observer) {
+        const {element, ancestors} = observer;
+
+        element.removeEventListener('change', observer.onChange, false);
+        observer.onChange = null;
+
+        this._elementMap.delete(element);
+
+        for (const ancestor of ancestors) {
+            const observers = this._elementAncestorMap.get(ancestor);
+            if (typeof observers === 'undefined') { continue; }
+
+            observers.delete(observer);
+            if (observers.size === 0) {
+                this._elementAncestorMap.delete(ancestor);
+            }
+        }
+    }
+
+    _isObserverStale(observer) {
+        const {element, type, metadata} = observer;
+        const nodeName = element.nodeName.toUpperCase();
+        return !(
+            type === (nodeName === 'INPUT' ? element.type : null) &&
+            this._compareElementMetadata(metadata, this._createElementMetadata(element))
+        );
+    }
+
+    _shouldIgnoreElement(element) {
+        for (const selector of this._ignoreSelectors) {
+            if (element.matches(selector)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    _getAncestors(node) {
+        const root = this._observingElement;
+        const results = [];
+        while (true) {
+            results.push(node);
+            if (node === root) { break; }
+            node = node.parentNode;
+            if (node === null) { break; }
+        }
+        return results;
+    }
+
+    _setElementValue(element, value) {
+        switch (element.nodeName.toUpperCase()) {
+            case 'INPUT':
+                switch (element.type) {
+                    case 'checkbox':
+                        element.checked = value;
+                        break;
+                    case 'text':
+                    case 'number':
+                        element.value = value;
+                        break;
+                }
+                break;
+            case 'TEXTAREA':
+            case 'SELECT':
+                element.value = value;
+                break;
+        }
+    }
+
+    _getElementValue(element) {
+        switch (element.nodeName.toUpperCase()) {
+            case 'INPUT':
+                switch (element.type) {
+                    case 'checkbox':
+                        return !!element.checked;
+                    case 'text':
+                        return `${element.value}`;
+                    case 'number':
+                        return this._getInputNumberValue(element);
+                }
+                break;
+            case 'TEXTAREA':
+            case 'SELECT':
+                return element.value;
+        }
+        return null;
+    }
+
+    _getInputNumberValue(element) {
+        let value = parseFloat(element.value);
+        if (!Number.isFinite(value)) { return 0; }
+
+        let {min, max, step} = element;
+        min = this._stringValueToNumberOrNull(min);
+        max = this._stringValueToNumberOrNull(max);
+        step = this._stringValueToNumberOrNull(step);
+        if (typeof min === 'number') { value = Math.max(value, min); }
+        if (typeof max === 'number') { value = Math.min(value, max); }
+        if (typeof step === 'number' && step !== 0) { value = Math.round(value / step) * step; }
+        return value;
+    }
+
+    _stringValueToNumberOrNull(value) {
+        if (typeof value !== 'string' || value.length === 0) {
+            return null;
+        }
+
+        const number = parseFloat(value);
+        return !Number.isNaN(number) ? number : null;
+    }
+}
diff --git a/ext/mixed/js/dom.js b/ext/mixed/js/dom.js
index 0e8f4462..59fea9f6 100644
--- a/ext/mixed/js/dom.js
+++ b/ext/mixed/js/dom.js
@@ -77,6 +77,24 @@ class DOM {
         return (typeof key === 'string' ? (key.length === 1 ? key.toUpperCase() : key) : '');
     }
 
+    static addFullscreenChangeEventListener(onFullscreenChanged, eventListenerCollection=null) {
+        const target = document;
+        const options = false;
+        const fullscreenEventNames = [
+            'fullscreenchange',
+            'MSFullscreenChange',
+            'mozfullscreenchange',
+            'webkitfullscreenchange'
+        ];
+        for (const eventName of fullscreenEventNames) {
+            if (eventListenerCollection === null) {
+                target.addEventListener(eventName, onFullscreenChanged, options);
+            } else {
+                eventListenerCollection.addEventListener(target, eventName, onFullscreenChanged, options);
+            }
+        }
+    }
+
     static getFullscreenElement() {
         return (
             document.fullscreenElement ||
@@ -86,4 +104,42 @@ class DOM {
             null
         );
     }
+
+    static getNodesInRange(range) {
+        const end = range.endContainer;
+        const nodes = [];
+        for (let node = range.startContainer; node !== null; node = DOM.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 (next === null) { break; }
+
+                node = next;
+            }
+        }
+        return next;
+    }
+
+    static anyNodeMatchesSelector(nodes, selector) {
+        const ELEMENT_NODE = Node.ELEMENT_NODE;
+        for (let node of nodes) {
+            for (; node !== null; node = node.parentNode) {
+                if (node.nodeType !== ELEMENT_NODE) { continue; }
+                if (node.matches(selector)) { return true; }
+                break;
+            }
+        }
+        return false;
+    }
 }
diff --git a/ext/mixed/js/dynamic-loader.js b/ext/mixed/js/dynamic-loader.js
index ce946109..981d1ee5 100644
--- a/ext/mixed/js/dynamic-loader.js
+++ b/ext/mixed/js/dynamic-loader.js
@@ -16,19 +16,41 @@
  */
 
 /* global
- * apiInjectStylesheet
+ * api
  */
 
 const dynamicLoader = (() => {
     const injectedStylesheets = new Map();
+    const injectedStylesheetsWithParent = new WeakMap();
 
-    async function loadStyle(id, type, value, useWebExtensionApi=false) {
+    function getInjectedStylesheet(id, parentNode) {
+        if (parentNode === null) {
+            return injectedStylesheets.get(id);
+        }
+        const map = injectedStylesheetsWithParent.get(parentNode);
+        return typeof map !== 'undefined' ? map.get(id) : void 0;
+    }
+
+    function setInjectedStylesheet(id, parentNode, value) {
+        if (parentNode === null) {
+            injectedStylesheets.set(id, value);
+            return;
+        }
+        let map = injectedStylesheetsWithParent.get(parentNode);
+        if (typeof map === 'undefined') {
+            map = new Map();
+            injectedStylesheetsWithParent.set(parentNode, map);
+        }
+        map.set(id, value);
+    }
+
+    async function loadStyle(id, type, value, useWebExtensionApi=false, parentNode=null) {
         if (useWebExtensionApi && yomichan.isExtensionUrl(window.location.href)) {
             // Permissions error will occur if trying to use the WebExtension API to inject into an extension page
             useWebExtensionApi = false;
         }
 
-        let styleNode = injectedStylesheets.get(id);
+        let styleNode = getInjectedStylesheet(id, parentNode);
         if (typeof styleNode !== 'undefined') {
             if (styleNode === null) {
                 // Previously injected via WebExtension API
@@ -38,21 +60,30 @@ const dynamicLoader = (() => {
             styleNode = null;
         }
 
+        if (type === 'file-content') {
+            value = await api.getStylesheetContent(value);
+            type = 'code';
+            useWebExtensionApi = false;
+        }
+
         if (useWebExtensionApi) {
             // Inject via WebExtension API
             if (styleNode !== null && styleNode.parentNode !== null) {
                 styleNode.parentNode.removeChild(styleNode);
             }
 
-            injectedStylesheets.set(id, null);
-            await apiInjectStylesheet(type, value);
+            setInjectedStylesheet(id, parentNode, null);
+            await api.injectStylesheet(type, value);
             return null;
         }
 
         // Create node in document
-        const parentNode = document.head;
-        if (parentNode === null) {
-            throw new Error('No parent node');
+        let parentNode2 = parentNode;
+        if (parentNode2 === null) {
+            parentNode2 = document.head;
+            if (parentNode2 === null) {
+                throw new Error('No parent node');
+            }
         }
 
         // Create or reuse node
@@ -74,12 +105,12 @@ const dynamicLoader = (() => {
         }
 
         // Update parent
-        if (styleNode.parentNode !== parentNode) {
-            parentNode.appendChild(styleNode);
+        if (styleNode.parentNode !== parentNode2) {
+            parentNode2.appendChild(styleNode);
         }
 
         // Add to map
-        injectedStylesheets.set(id, styleNode);
+        setInjectedStylesheet(id, parentNode, styleNode);
         return styleNode;
     }
 
diff --git a/ext/mixed/js/environment.js b/ext/mixed/js/environment.js
index e5bc20a7..5bd84010 100644
--- a/ext/mixed/js/environment.js
+++ b/ext/mixed/js/environment.js
@@ -32,17 +32,40 @@ class Environment {
 
     async _loadEnvironmentInfo() {
         const browser = await this._getBrowser();
-        const platform = await new Promise((resolve) => chrome.runtime.getPlatformInfo(resolve));
-        const modifierInfo = this._getModifierInfo(browser, platform.os);
+        const os = await this._getOperatingSystem();
+        const modifierInfo = this._getModifierInfo(browser, os);
         return {
             browser,
-            platform: {
-                os: platform.os
-            },
+            platform: {os},
             modifiers: modifierInfo
         };
     }
 
+    async _getOperatingSystem() {
+        try {
+            const {os} = await this._getPlatformInfo();
+            if (typeof os === 'string') {
+                return os;
+            }
+        } catch (e) {
+            // NOP
+        }
+        return 'unknown';
+    }
+
+    _getPlatformInfo() {
+        return new Promise((resolve, reject) => {
+            chrome.runtime.getPlatformInfo((result) => {
+                const error = chrome.runtime.lastError;
+                if (error) {
+                    reject(error);
+                } else {
+                    resolve(result);
+                }
+            });
+        });
+    }
+
     async _getBrowser() {
         if (EXTENSION_IS_BROWSER_EDGE) {
             return 'edge';
@@ -96,8 +119,15 @@ class Environment {
                     ['meta', 'Super']
                 ];
                 break;
-            default:
-                throw new Error(`Invalid OS: ${os}`);
+            default: // 'unknown', etc
+                separator = ' + ';
+                osKeys = [
+                    ['alt', 'Alt'],
+                    ['ctrl', 'Ctrl'],
+                    ['shift', 'Shift'],
+                    ['meta', 'Meta']
+                ];
+                break;
         }
 
         const isFirefox = (browser === 'firefox' || browser === 'firefox-mobile');
diff --git a/ext/mixed/js/media-loader.js b/ext/mixed/js/media-loader.js
index 64ccd715..fc6e93d1 100644
--- a/ext/mixed/js/media-loader.js
+++ b/ext/mixed/js/media-loader.js
@@ -16,7 +16,7 @@
  */
 
 /* global
- * apiGetMedia
+ * api
  */
 
 class MediaLoader {
@@ -84,7 +84,7 @@ class MediaLoader {
 
     async _getMediaData(path, dictionaryName, cachedData) {
         const token = this._token;
-        const data = (await apiGetMedia([{path, dictionaryName}]))[0];
+        const data = (await api.getMedia([{path, dictionaryName}]))[0];
         if (token === this._token && data !== null) {
             const contentArrayBuffer = this._base64ToArrayBuffer(data.content);
             const blob = new Blob([contentArrayBuffer], {type: data.mediaType});
diff --git a/ext/mixed/js/task-accumulator.js b/ext/mixed/js/task-accumulator.js
new file mode 100644
index 00000000..5c6fe312
--- /dev/null
+++ b/ext/mixed/js/task-accumulator.js
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2020  Yomichan Authors
+ *
+ * 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 <https://www.gnu.org/licenses/>.
+ */
+
+class TaskAccumulator {
+    constructor(runTasks) {
+        this._deferPromise = null;
+        this._activePromise = null;
+        this._tasks = [];
+        this._tasksActive = [];
+        this._uniqueTasks = new Map();
+        this._uniqueTasksActive = new Map();
+        this._runTasksBind = this._runTasks.bind(this);
+        this._tasksCompleteBind = this._tasksComplete.bind(this);
+        this._runTasks = runTasks;
+    }
+
+    enqueue(key, data) {
+        if (this._deferPromise === null) {
+            const promise = this._activePromise !== null ? this._activePromise : Promise.resolve();
+            this._deferPromise = promise.then(this._runTasksBind);
+        }
+
+        const task = {data, stale: false};
+        if (key !== null) {
+            const activeTaskInfo = this._uniqueTasksActive.get(key);
+            if (typeof activeTaskInfo !== 'undefined') {
+                activeTaskInfo.stale = true;
+            }
+
+            this._uniqueTasks.set(key, task);
+        } else {
+            this._tasks.push(task);
+        }
+
+        return this._deferPromise;
+    }
+
+    _runTasks() {
+        this._deferPromise = null;
+
+        // Swap
+        [this._tasks, this._tasksActive] = [this._tasksActive, this._tasks];
+        [this._uniqueTasks, this._uniqueTasksActive] = [this._uniqueTasksActive, this._uniqueTasks];
+
+        const promise = this._runTasksAsync();
+        this._activePromise = promise.then(this._tasksCompleteBind);
+        return this._activePromise;
+    }
+
+    async _runTasksAsync() {
+        try {
+            const allTasks = [
+                ...this._tasksActive.map((taskInfo) => [null, taskInfo]),
+                ...this._uniqueTasksActive.entries()
+            ];
+            await this._runTasks(allTasks);
+        } catch (e) {
+            yomichan.logError(e);
+        }
+    }
+
+    _tasksComplete() {
+        this._tasksActive.length = 0;
+        this._uniqueTasksActive.clear();
+        this._activePromise = null;
+    }
+}
diff --git a/ext/mixed/js/text-scanner.js b/ext/mixed/js/text-scanner.js
index b8688b08..7c705fc8 100644
--- a/ext/mixed/js/text-scanner.js
+++ b/ext/mixed/js/text-scanner.js
@@ -17,7 +17,6 @@
 
 /* global
  * DOM
- * TextSourceRange
  * docRangeFromPoint
  */
 
@@ -29,6 +28,7 @@ class TextScanner extends EventDispatcher {
         this._ignorePoint = ignorePoint;
         this._search = search;
 
+        this._isPrepared = false;
         this._ignoreNodes = null;
 
         this._causeCurrent = null;
@@ -70,10 +70,15 @@ class TextScanner extends EventDispatcher {
         return this._causeCurrent;
     }
 
+    prepare() {
+        this._isPrepared = true;
+        this.setEnabled(this._enabled);
+    }
+
     setEnabled(enabled) {
         this._eventListeners.removeAllEventListeners();
         this._enabled = enabled;
-        if (this._enabled) {
+        if (this._enabled && this._isPrepared) {
             this._hookEvents();
         } else {
             this.clearSelection(true);
@@ -119,20 +124,20 @@ class TextScanner extends EventDispatcher {
         }
     }
 
-    getTextSourceContent(textSource, length) {
+    getTextSourceContent(textSource, length, layoutAwareScan) {
         const clonedTextSource = textSource.clone();
 
-        clonedTextSource.setEndOffset(length);
+        clonedTextSource.setEndOffset(length, layoutAwareScan);
 
         if (this._ignoreNodes !== null && clonedTextSource.range) {
             length = clonedTextSource.text().length;
             while (clonedTextSource.range && length > 0) {
-                const nodes = TextSourceRange.getNodesInRange(clonedTextSource.range);
-                if (!TextSourceRange.anyNodeMatchesSelector(nodes, this._ignoreNodes)) {
+                const nodes = DOM.getNodesInRange(clonedTextSource.range);
+                if (!DOM.anyNodeMatchesSelector(nodes, this._ignoreNodes)) {
                     break;
                 }
                 --length;
-                clonedTextSource.setEndOffset(length);
+                clonedTextSource.setEndOffset(length, layoutAwareScan);
             }
         }