The Tor Browser: browser/components/preferences/in-content/advanced.js@4ab42b5ab56c (annotated)

browser/components/preferences/in-content/advanced.js@4ab42b5ab56c (annotated)

browser/components/preferences/in-content/advanced.js

Wed, 31 Dec 2014 07:53:36 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 07:53:36 +0100
branch: TOR_BUG_3246
changeset 5: 4ab42b5ab56c
permissions: -rw-r--r--

Correct small whitespace inconsistency, lost while renaming variables.

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 // Load DownloadUtils module for convertByteUnits
 Components.utils.import("resource://gre/modules/DownloadUtils.jsm");
 Components.utils.import("resource://gre/modules/LoadContextInfo.jsm");
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
 var gAdvancedPane = {
   _inited: false,
   /**
    * Brings the appropriate tab to the front and initializes various bits of UI.
    */
   init: function ()
   {
     this._inited = true;
     var advancedPrefs = document.getElementById("advancedPrefs");
     var preference = document.getElementById("browser.preferences.advanced.selectedTabIndex");
     if (preference.value !== null)
         advancedPrefs.selectedIndex = preference.value;
 #ifdef HAVE_SHELL_SERVICE
     this.updateSetDefaultBrowser();
 #ifdef XP_WIN
     // In Windows 8 we launch the control panel since it's the only
     // way to get all file type association prefs. So we don't know
     // when the user will select the default.  We refresh here periodically
     // in case the default changes.  On other Windows OS's defaults can also
     // be set while the prefs are open.
     window.setInterval(this.updateSetDefaultBrowser, 1000);
 #ifdef MOZ_METRO
     // Pre Windows 8, we should hide the update related settings
     // for the Metro browser
     let version = Components.classes["@mozilla.org/system-info;1"].
                   getService(Components.interfaces.nsIPropertyBag2).
                   getProperty("version");
     let preWin8 = parseFloat(version) < 6.2;
     this._showingWin8Prefs = !preWin8;
     if (preWin8) {
       ["autoMetro", "autoMetroIndent"].forEach(
         function(id) document.getElementById(id).collapsed = true
       );
     } else {
       let brandShortName =
         document.getElementById("bundleBrand").getString("brandShortName");
       let bundlePrefs = document.getElementById("bundlePreferences");
       let autoDesktop = document.getElementById("autoDesktop");
       autoDesktop.label =
         bundlePrefs.getFormattedString("updateAutoDesktop.label",
                                        [brandShortName]);
       autoDesktop.accessKey =
         bundlePrefs.getString("updateAutoDesktop.accessKey");
     }
 #endif
 #endif
 #endif
 #ifdef MOZ_UPDATER
     this.updateReadPrefs();
 #endif
     this.updateOfflineApps();
 #ifdef MOZ_CRASHREPORTER
     this.initSubmitCrashes();
 #endif
     this.initTelemetry();
 #ifdef MOZ_SERVICES_HEALTHREPORT
     this.initSubmitHealthReport();
 #endif
     this.updateActualCacheSize();
     this.updateActualAppCacheSize();
   },
   /**
    * Stores the identity of the current tab in preferences so that the selected
    * tab can be persisted between openings of the preferences window.
    */
   tabSelectionChanged: function ()
   {
     if (!this._inited)
       return;
     var advancedPrefs = document.getElementById("advancedPrefs");
     var preference = document.getElementById("browser.preferences.advanced.selectedTabIndex");
     preference.valueFromPreferences = advancedPrefs.selectedIndex;
   },
   // GENERAL TAB
   /*
    * Preferences:
    *
    * accessibility.browsewithcaret
    * - true enables keyboard navigation and selection within web pages using a
    *   visible caret, false uses normal keyboard navigation with no caret
    * accessibility.typeaheadfind
    * - when set to true, typing outside text areas and input boxes will
    *   automatically start searching for what's typed within the current
    *   document; when set to false, no search action happens
    * general.autoScroll
    * - when set to true, clicking the scroll wheel on the mouse activates a
    *   mouse mode where moving the mouse down scrolls the document downward with
    *   speed correlated with the distance of the cursor from the original
    *   position at which the click occurred (and likewise with movement upward);
    *   if false, this behavior is disabled
    * general.smoothScroll
    * - set to true to enable finer page scrolling than line-by-line on page-up,
    *   page-down, and other such page movements
    * layout.spellcheckDefault
    * - an integer:
    *     0  disables spellchecking
    *     1  enables spellchecking, but only for multiline text fields
    *     2  enables spellchecking for all text fields
    */
   /**
    * Stores the original value of the spellchecking preference to enable proper
    * restoration if unchanged (since we're mapping a tristate onto a checkbox).
    */
   _storedSpellCheck: 0,
   /**
    * Returns true if any spellchecking is enabled and false otherwise, caching
    * the current value to enable proper pref restoration if the checkbox is
    * never changed.
    */
   readCheckSpelling: function ()
   {
     var pref = document.getElementById("layout.spellcheckDefault");
     this._storedSpellCheck = pref.value;
     return (pref.value != 0);
   },
   /**
    * Returns the value of the spellchecking preference represented by UI,
    * preserving the preference's "hidden" value if the preference is
    * unchanged and represents a value not strictly allowed in UI.
    */
   writeCheckSpelling: function ()
   {
     var checkbox = document.getElementById("checkSpelling");
     return checkbox.checked ? (this._storedSpellCheck == 2 ? 2 : 1) : 0;
   },
   /**
    * When the user toggles the layers.acceleration.disabled pref,
    * sync its new value to the gfx.direct2d.disabled pref too.
    */
   updateHardwareAcceleration: function()
   {
 #ifdef XP_WIN
     var fromPref = document.getElementById("layers.acceleration.disabled");
     var toPref = document.getElementById("gfx.direct2d.disabled");
     toPref.value = fromPref.value;
 #endif
   },
   // DATA CHOICES TAB
   /**
    * Set up or hide the Learn More links for various data collection options
    */
   _setupLearnMoreLink: function (pref, element) {
     // set up the Learn More link with the correct URL
     let url = Services.prefs.getCharPref(pref);
     let el = document.getElementById(element);
     if (url) {
       el.setAttribute("href", url);
     } else {
       el.setAttribute("hidden", "true");
     }
   },
   /**
    *
    */
   initSubmitCrashes: function ()
   {
     this._setupLearnMoreLink("toolkit.crashreporter.infoURL",
                              "crashReporterLearnMore");
     var checkbox = document.getElementById("submitCrashesBox");
     try {
       var cr = Components.classes["@mozilla.org/toolkit/crash-reporter;1"].
                getService(Components.interfaces.nsICrashReporter);
       checkbox.checked = cr.submitReports;
     } catch (e) {
       checkbox.style.display = "none";
     }
   },
   /**
    *
    */
   updateSubmitCrashes: function ()
   {
     var checkbox = document.getElementById("submitCrashesBox");
     try {
       var cr = Components.classes["@mozilla.org/toolkit/crash-reporter;1"].
                getService(Components.interfaces.nsICrashReporter);
       cr.submitReports = checkbox.checked;
     } catch (e) { }
   },
   /**
    * The preference/checkbox is configured in XUL.
    *
    * In all cases, set up the Learn More link sanely.
    */
   initTelemetry: function ()
   {
 #ifdef MOZ_TELEMETRY_REPORTING
     this._setupLearnMoreLink("toolkit.telemetry.infoURL", "telemetryLearnMore");
 #endif
   },
 #ifdef MOZ_SERVICES_HEALTHREPORT
   /**
    * Initialize the health report service reference and checkbox.
    */
   initSubmitHealthReport: function () {
     this._setupLearnMoreLink("datareporting.healthreport.infoURL", "FHRLearnMore");
     let policy = Components.classes["@mozilla.org/datareporting/service;1"]
                                    .getService(Components.interfaces.nsISupports)
                                    .wrappedJSObject
                                    .policy;
     let checkbox = document.getElementById("submitHealthReportBox");
     if (!policy || policy.healthReportUploadLocked) {
       checkbox.setAttribute("disabled", "true");
       return;
     }
     checkbox.checked = policy.healthReportUploadEnabled;
   },
   /**
    * Update the health report policy acceptance with state from checkbox.
    */
   updateSubmitHealthReport: function () {
     let policy = Components.classes["@mozilla.org/datareporting/service;1"]
                                    .getService(Components.interfaces.nsISupports)
                                    .wrappedJSObject
                                    .policy;
     if (!policy) {
       return;
     }
     let checkbox = document.getElementById("submitHealthReportBox");
     policy.recordHealthReportUploadEnabled(checkbox.checked,
                                            "Checkbox from preferences pane");
   },
 #endif
   // NETWORK TAB
   /*
    * Preferences:
    *
    * browser.cache.disk.capacity
    * - the size of the browser cache in KB
    * - Only used if browser.cache.disk.smart_size.enabled is disabled
    */
   /**
    * Displays a dialog in which proxy settings may be changed.
    */
   showConnections: function ()
   {
     openDialog("chrome://browser/content/preferences/connection.xul",
                "mozilla:connectionmanager",
                "modal=yes",
                null);
   },
   // Retrieves the amount of space currently used by disk cache
   updateActualCacheSize: function ()
   {
     var actualSizeLabel = document.getElementById("actualDiskCacheSize");
     var prefStrBundle = document.getElementById("bundlePreferences");
     // Needs to root the observer since cache service keeps only a weak reference.
     this.observer = {
       onNetworkCacheDiskConsumption: function(consumption) {
         var size = DownloadUtils.convertByteUnits(consumption);
         actualSizeLabel.value = prefStrBundle.getFormattedString("actualDiskCacheSize", size);
       },
       QueryInterface: XPCOMUtils.generateQI([
         Components.interfaces.nsICacheStorageConsumptionObserver,
         Components.interfaces.nsISupportsWeakReference
       ])
     };
     actualSizeLabel.value = prefStrBundle.getString("actualDiskCacheSizeCalculated");
     var cacheService =
       Components.classes["@mozilla.org/netwerk/cache-storage-service;1"]
                 .getService(Components.interfaces.nsICacheStorageService);
     cacheService.asyncGetDiskConsumption(this.observer);
   },
   // Retrieves the amount of space currently used by offline cache
   updateActualAppCacheSize: function ()
   {
     var visitor = {
       visitDevice: function (deviceID, deviceInfo)
       {
         if (deviceID == "offline") {
           var actualSizeLabel = document.getElementById("actualAppCacheSize");
           var sizeStrings = DownloadUtils.convertByteUnits(deviceInfo.totalSize);
           var prefStrBundle = document.getElementById("bundlePreferences");
           var sizeStr = prefStrBundle.getFormattedString("actualAppCacheSize", sizeStrings);
           actualSizeLabel.value = sizeStr;
         }
         // Do not enumerate entries
         return false;
       },
       visitEntry: function (deviceID, entryInfo)
       {
         // Do not enumerate entries.
         return false;
       }
     };
     var cacheService =
       Components.classes["@mozilla.org/network/cache-service;1"]
                 .getService(Components.interfaces.nsICacheService);
     cacheService.visitEntries(visitor);
   },
   updateCacheSizeUI: function (smartSizeEnabled)
   {
     document.getElementById("useCacheBefore").disabled = smartSizeEnabled;
     document.getElementById("cacheSize").disabled = smartSizeEnabled;
     document.getElementById("useCacheAfter").disabled = smartSizeEnabled;
   },
   readSmartSizeEnabled: function ()
   {
     // The smart_size.enabled preference element is inverted="true", so its
     // value is the opposite of the actual pref value
     var disabled = document.getElementById("browser.cache.disk.smart_size.enabled").value;
     this.updateCacheSizeUI(!disabled);
   },
   /**
    * Converts the cache size from units of KB to units of MB and returns that
    * value.
    */
   readCacheSize: function ()
   {
     var preference = document.getElementById("browser.cache.disk.capacity");
     return preference.value / 1024;
   },
   /**
    * Converts the cache size as specified in UI (in MB) to KB and returns that
    * value.
    */
   writeCacheSize: function ()
   {
     var cacheSize = document.getElementById("cacheSize");
     var intValue = parseInt(cacheSize.value, 10);
     return isNaN(intValue) ? 0 : intValue * 1024;
   },
   /**
    * Clears the cache.
    */
   clearCache: function ()
   {
     var cache = Components.classes["@mozilla.org/netwerk/cache-storage-service;1"]
                                  .getService(Components.interfaces.nsICacheStorageService);
     try {
       cache.clear();
     } catch(ex) {}
     this.updateActualCacheSize();
   },
   /**
    * Clears the application cache.
    */
   clearOfflineAppCache: function ()
   {
     Components.utils.import("resource:///modules/offlineAppCache.jsm");
     OfflineAppCacheHelper.clear();
     this.updateActualAppCacheSize();
     this.updateOfflineApps();
   },
   readOfflineNotify: function()
   {
     var pref = document.getElementById("browser.offline-apps.notify");
     var button = document.getElementById("offlineNotifyExceptions");
     button.disabled = !pref.value;
     return pref.value;
   },
   showOfflineExceptions: function()
   {
     var bundlePreferences = document.getElementById("bundlePreferences");
     var params = { blockVisible     : false,
                    sessionVisible   : false,
                    allowVisible     : false,
                    prefilledHost    : "",
                    permissionType   : "offline-app",
                    manageCapability : Components.interfaces.nsIPermissionManager.DENY_ACTION,
                    windowTitle      : bundlePreferences.getString("offlinepermissionstitle"),
                    introText        : bundlePreferences.getString("offlinepermissionstext") };
     openDialog("chrome://browser/content/preferences/permissions.xul",
                "Browser:Permissions",
                "modal=yes",
                params);
   },
   // XXX: duplicated in browser.js
   _getOfflineAppUsage: function (host, groups)
   {
     var cacheService = Components.classes["@mozilla.org/network/application-cache-service;1"].
                        getService(Components.interfaces.nsIApplicationCacheService);
     if (!groups)
       groups = cacheService.getGroups();
     var ios = Components.classes["@mozilla.org/network/io-service;1"].
               getService(Components.interfaces.nsIIOService);
     var usage = 0;
     for (var i = 0; i < groups.length; i++) {
       var uri = ios.newURI(groups[i], null, null);
       if (uri.asciiHost == host) {
         var cache = cacheService.getActiveCache(groups[i]);
         usage += cache.usage;
       }
     }
     return usage;
   },
   /**
    * Updates the list of offline applications
    */
   updateOfflineApps: function ()
   {
     var pm = Components.classes["@mozilla.org/permissionmanager;1"]
                        .getService(Components.interfaces.nsIPermissionManager);
     var list = document.getElementById("offlineAppsList");
     while (list.firstChild) {
       list.removeChild(list.firstChild);
     }
     var cacheService = Components.classes["@mozilla.org/network/application-cache-service;1"].
                        getService(Components.interfaces.nsIApplicationCacheService);
     var groups = cacheService.getGroups();
     var bundle = document.getElementById("bundlePreferences");
     var enumerator = pm.enumerator;
     while (enumerator.hasMoreElements()) {
       var perm = enumerator.getNext().QueryInterface(Components.interfaces.nsIPermission);
       if (perm.type == "offline-app" &&
           perm.capability != Components.interfaces.nsIPermissionManager.DEFAULT_ACTION &&
           perm.capability != Components.interfaces.nsIPermissionManager.DENY_ACTION) {
         var row = document.createElement("listitem");
         row.id = "";
         row.className = "offlineapp";
         row.setAttribute("host", perm.host);
         var converted = DownloadUtils.
                         convertByteUnits(this._getOfflineAppUsage(perm.host, groups));
         row.setAttribute("usage",
                          bundle.getFormattedString("offlineAppUsage",
                                                    converted));
         list.appendChild(row);
       }
     }
   },
   offlineAppSelected: function()
   {
     var removeButton = document.getElementById("offlineAppsListRemove");
     var list = document.getElementById("offlineAppsList");
     if (list.selectedItem) {
       removeButton.setAttribute("disabled", "false");
     } else {
       removeButton.setAttribute("disabled", "true");
     }
   },
   removeOfflineApp: function()
   {
     var list = document.getElementById("offlineAppsList");
     var item = list.selectedItem;
     var host = item.getAttribute("host");
     var prompts = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]
                             .getService(Components.interfaces.nsIPromptService);
     var flags = prompts.BUTTON_TITLE_IS_STRING * prompts.BUTTON_POS_0 +
                 prompts.BUTTON_TITLE_CANCEL * prompts.BUTTON_POS_1;
     var bundle = document.getElementById("bundlePreferences");
     var title = bundle.getString("offlineAppRemoveTitle");
     var prompt = bundle.getFormattedString("offlineAppRemovePrompt", [host]);
     var confirm = bundle.getString("offlineAppRemoveConfirm");
     var result = prompts.confirmEx(window, title, prompt, flags, confirm,
                                    null, null, null, {});
     if (result != 0)
       return;
     // clear offline cache entries
     var cacheService = Components.classes["@mozilla.org/network/application-cache-service;1"].
                        getService(Components.interfaces.nsIApplicationCacheService);
     var ios = Components.classes["@mozilla.org/network/io-service;1"].
               getService(Components.interfaces.nsIIOService);
     var groups = cacheService.getGroups();
     for (var i = 0; i < groups.length; i++) {
         var uri = ios.newURI(groups[i], null, null);
         if (uri.asciiHost == host) {
             var cache = cacheService.getActiveCache(groups[i]);
             cache.discard();
         }
     }
     // remove the permission
     var pm = Components.classes["@mozilla.org/permissionmanager;1"]
                        .getService(Components.interfaces.nsIPermissionManager);
     pm.remove(host, "offline-app",
               Components.interfaces.nsIPermissionManager.ALLOW_ACTION);
     pm.remove(host, "offline-app",
               Components.interfaces.nsIOfflineCacheUpdateService.ALLOW_NO_WARN);
     list.removeChild(item);
     gAdvancedPane.offlineAppSelected();
     this.updateActualAppCacheSize();
   },
   // UPDATE TAB
   /*
    * Preferences:
    *
    * app.update.enabled
    * - true if updates to the application are enabled, false otherwise
    * extensions.update.enabled
    * - true if updates to extensions and themes are enabled, false otherwise
    * browser.search.update
    * - true if updates to search engines are enabled, false otherwise
    * app.update.auto
    * - true if updates should be automatically downloaded and installed,
    *   possibly with a warning if incompatible extensions are installed (see
    *   app.update.mode); false if the user should be asked what he wants to do
    *   when an update is available
    * app.update.mode
    * - an integer:
    *     0    do not warn if an update will disable extensions or themes
    *     1    warn if an update will disable extensions or themes
    *     2    warn if an update will disable extensions or themes *or* if the
    *          update is a major update
    */
 #ifdef MOZ_UPDATER
   /**
    * Selects the item of the radiogroup, and sets the warnIncompatible checkbox
    * based on the pref values and locked states.
    *
    * UI state matrix for update preference conditions
    *
    * UI Components:                              Preferences
    * Radiogroup                                  i   = app.update.enabled
    * Warn before disabling extensions checkbox   ii  = app.update.auto
    *                                             iii = app.update.mode
    *
    * Disabled states:
    * Element           pref  value  locked  disabled
    * radiogroup        i     t/f    f       false
    *                   i     t/f    *t*     *true*
    *                   ii    t/f    f       false
    *                   ii    t/f    *t*     *true*
    *                   iii   0/1/2  t/f     false
    * warnIncompatible  i     t      f       false
    *                   i     t      *t*     *true*
    *                   i     *f*    t/f     *true*
    *                   ii    t      f       false
    *                   ii    t      *t*     *true*
    *                   ii    *f*    t/f     *true*
    *                   iii   0/1/2  f       false
    *                   iii   0/1/2  *t*     *true*
    */
   updateReadPrefs: function ()
   {
     var enabledPref = document.getElementById("app.update.enabled");
     var autoPref = document.getElementById("app.update.auto");
 #ifdef XP_WIN
 #ifdef MOZ_METRO
     var metroEnabledPref = document.getElementById("app.update.metro.enabled");
 #endif
 #endif
     var radiogroup = document.getElementById("updateRadioGroup");
     if (!enabledPref.value)   // Don't care for autoPref.value in this case.
       radiogroup.value="manual";    // 3. Never check for updates.
 #ifdef XP_WIN
 #ifdef MOZ_METRO
     // enabledPref.value && autoPref.value && metroEnabledPref.value
     else if (metroEnabledPref.value && this._showingWin8Prefs)
       radiogroup.value="autoMetro"; // 0. Automatically install updates
 #endif
 #endif
     else if (autoPref.value)  // enabledPref.value && autoPref.value
       radiogroup.value="auto";      // 1. Automatically install updates
     else                      // enabledPref.value && !autoPref.value
       radiogroup.value="checkOnly"; // 2. Check, but let me choose
     var canCheck = Components.classes["@mozilla.org/updates/update-service;1"].
                      getService(Components.interfaces.nsIApplicationUpdateService).
                      canCheckForUpdates;
     // canCheck is false if the enabledPref is false and locked,
     // or the binary platform or OS version is not known.
     // A locked pref is sufficient to disable the radiogroup.
     radiogroup.disabled = !canCheck || enabledPref.locked || autoPref.locked;
     var modePref = document.getElementById("app.update.mode");
     var warnIncompatible = document.getElementById("warnIncompatible");
     // the warnIncompatible checkbox value is set by readAddonWarn
     warnIncompatible.disabled = radiogroup.disabled || modePref.locked ||
                                 !enabledPref.value || !autoPref.value;
 #ifdef XP_WIN
 #ifdef MOZ_METRO
     if (this._showingWin8Prefs) {
       warnIncompatible.disabled |= metroEnabledPref.value;
       warnIncompatible.checked |= metroEnabledPref.value;
     }
 #endif
 #endif
 #ifdef MOZ_MAINTENANCE_SERVICE
     // Check to see if the maintenance service is installed.
     // If it is don't show the preference at all.
     var installed;
     try {
       var wrk = Components.classes["@mozilla.org/windows-registry-key;1"]
                 .createInstance(Components.interfaces.nsIWindowsRegKey);
       wrk.open(wrk.ROOT_KEY_LOCAL_MACHINE,
                "SOFTWARE\\Mozilla\\MaintenanceService",
                wrk.ACCESS_READ | wrk.WOW64_64);
       installed = wrk.readIntValue("Installed");
       wrk.close();
     } catch(e) {
     }
     if (installed != 1) {
       document.getElementById("useService").hidden = true;
     }
 #endif
   },
   /**
    * Sets the pref values based on the selected item of the radiogroup,
    * and sets the disabled state of the warnIncompatible checkbox accordingly.
    */
   updateWritePrefs: function ()
   {
     var enabledPref = document.getElementById("app.update.enabled");
     var autoPref = document.getElementById("app.update.auto");
     var modePref = document.getElementById("app.update.mode");
 #ifdef XP_WIN
 #ifdef MOZ_METRO
     var metroEnabledPref = document.getElementById("app.update.metro.enabled");
     // Initialize the pref to false only if we're showing the option
     if (this._showingWin8Prefs) {
       metroEnabledPref.value = false;
     }
 #endif
 #endif
     var radiogroup = document.getElementById("updateRadioGroup");
     switch (radiogroup.value) {
       case "auto":      // 1. Automatically install updates for Desktop only
         enabledPref.value = true;
         autoPref.value = true;
         break;
 #ifdef XP_WIN
 #ifdef MOZ_METRO
       case "autoMetro": // 0. Automatically install updates for both Metro and Desktop
         enabledPref.value = true;
         autoPref.value = true;
         metroEnabledPref.value = true;
         modePref.value = 1;
         break;
 #endif
 #endif
       case "checkOnly": // 2. Check, but let me choose
         enabledPref.value = true;
         autoPref.value = false;
         break;
       case "manual":    // 3. Never check for updates.
         enabledPref.value = false;
         autoPref.value = false;
     }
     var warnIncompatible = document.getElementById("warnIncompatible");
     warnIncompatible.disabled = enabledPref.locked || !enabledPref.value ||
                                 autoPref.locked || !autoPref.value ||
                                 modePref.locked;
 #ifdef XP_WIN
 #ifdef MOZ_METRO
     if (this._showingWin8Prefs) {
       warnIncompatible.disabled |= metroEnabledPref.value;
       warnIncompatible.checked |= metroEnabledPref.value;
     }
 #endif
 #endif
   },
   /**
    * Stores the value of the app.update.mode preference, which is a tristate
    * integer preference.  We store the value here so that we can properly
    * restore the preference value if the UI reflecting the preference value
    * is in a state which can represent either of two integer values (as
    * opposed to only one possible value in the other UI state).
    */
   _modePreference: -1,
   /**
    * Reads the app.update.mode preference and converts its value into a
    * true/false value for use in determining whether the "Warn me if this will
    * disable extensions or themes" checkbox is checked.  We also save the value
    * of the preference so that the preference value can be properly restored if
    * the user's preferences cannot adequately be expressed by a single checkbox.
    *
    * app.update.mode          Checkbox State    Meaning
    * 0                        Unchecked         Do not warn
    * 1                        Checked           Warn if there are incompatibilities
    * 2                        Checked           Warn if there are incompatibilities,
    *                                            or the update is major.
    */
   readAddonWarn: function ()
   {
     var preference = document.getElementById("app.update.mode");
     var warn = preference.value != 0;
     gAdvancedPane._modePreference = warn ? preference.value : 1;
     return warn;
   },
   /**
    * Converts the state of the "Warn me if this will disable extensions or
    * themes" checkbox into the integer preference which represents it,
    * returning that value.
    */
   writeAddonWarn: function ()
   {
     var warnIncompatible = document.getElementById("warnIncompatible");
     return !warnIncompatible.checked ? 0 : gAdvancedPane._modePreference;
   },
   /**
    * Displays the history of installed updates.
    */
   showUpdates: function ()
   {
     var prompter = Components.classes["@mozilla.org/updates/update-prompt;1"]
                              .createInstance(Components.interfaces.nsIUpdatePrompt);
     prompter.showUpdateHistory(window);
   },
 #endif
   // ENCRYPTION TAB
   /*
    * Preferences:
    *
    * security.default_personal_cert
    * - a string:
    *     "Select Automatically"   select a certificate automatically when a site
    *                              requests one
    *     "Ask Every Time"         present a dialog to the user so he can select
    *                              the certificate to use on a site which
    *                              requests one
    */
   /**
    * Displays the user's certificates and associated options.
    */
   showCertificates: function ()
   {
     openDialog("chrome://pippki/content/certManager.xul",
                "mozilla:certmanager",
                "modal=yes", null);
   },
   /**
    * Displays a dialog in which OCSP preferences can be configured.
    */
   showOCSP: function ()
   {
     openDialog("chrome://mozapps/content/preferences/ocsp.xul",
                "mozilla:crlmanager",
                "modal=yes", null);
   },
   /**
    * Displays a dialog from which the user can manage his security devices.
    */
   showSecurityDevices: function ()
   {
     openDialog("chrome://pippki/content/device_manager.xul",
                "mozilla:devicemanager",
                "modal=yes", null);
   }
 #ifdef HAVE_SHELL_SERVICE
   ,
   // SYSTEM DEFAULTS
   /*
    * Preferences:
    *
    * browser.shell.checkDefault
    * - true if a default-browser check (and prompt to make it so if necessary)
    *   occurs at startup, false otherwise
    */
   /**
    * Show button for setting browser as default browser or information that
    * browser is already the default browser.
    */
   updateSetDefaultBrowser: function()
   {
     let shellSvc = getShellService();
     let setDefaultPane = document.getElementById("setDefaultPane");
     if (!shellSvc) {
       setDefaultPane.hidden = true;
       document.getElementById("alwaysCheckDefault").disabled = true;
       return;
     }
     let selectedIndex =
       shellSvc.isDefaultBrowser(false, true) ? 1 : 0;
     setDefaultPane.selectedIndex = selectedIndex;
   },
   /**
    * Set browser as the operating system default browser.
    */
   setDefaultBrowser: function()
   {
     let shellSvc = getShellService();
     if (!shellSvc)
       return;
     shellSvc.setDefaultBrowser(true, false);
     let selectedIndex =
       shellSvc.isDefaultBrowser(false, true) ? 1 : 0;
     document.getElementById("setDefaultPane").selectedIndex = selectedIndex;
   }
 #endif
 };