Add 'with_appindicator' hidden pref.

This may be useful for StatusNotifierItem-ready environments which still support
ICCCM/EWMH, whereby FireTray may be less limited.

We'll just make it a hidden pref for now as the related UI is a nightmare.

README.md

@@ -20,6 +20,7 @@ Features
   * show icon only when hidden to tray
   * mouse scroll on tray icon shows/hides
   * GTK-themable icons
+  * StatusNotifierItem support (can be disabled by `with_appindicator` hidden pref)
   * customizable tray icons
   * popup menu (show/hide individual windows, open new windows, quit)
   * command-line `-firetrayShowHide` option (useful for window manager's keyboard shortcuts)

src/defaults/preferences/prefs.js

@@ -39,3 +39,5 @@ pref("extensions.firetray.excluded_folders_flags", 1077956384);
 // exposed in 1 tree, hence 2 branches: serverTypes, excludedAccounts
 pref("extensions.firetray.mail_accounts", '{ "serverTypes": {"pop3":{"order":1,"excluded":false}, "imap":{"order":1,"excluded":false}, "movemail":{"order":2,"excluded":true}, "none":{"order":3,"excluded":false}, "rss":{"order":4,"excluded":true}, "nntp":{"order":5,"excluded":true}, "exquilla":{"order":6,"excluded":true}}, "excludedAccounts": [] }'); // JSON
 pref("extensions.firetray.only_favorite_folders", false);
+
+pref("extensions.firetray.with_appindicator", true);

src/modules/linux/FiretrayStatusIcon.jsm

@@ -26,6 +26,7 @@ firetray.StatusIcon = {
   prefNewMailIconNames: null,
   defaultAppIconName: null,
   defaultNewMailIconName: null,
+  canAppIndicator: null,
 
   init: function() {
     this.defineIconNames();
@@ -34,7 +35,11 @@ firetray.StatusIcon = {
     // StatusIcon implementations, PopupMenu must be initialized *after*
     // implemenations are imported.
     Cu.import("resource://firetray/ctypes/linux/appindicator.jsm");
-    if (appind3.available() && this.dbusNotificationWatcherReady()) {
+    this.canAppIndicator =
+      (appind3.available() && this.dbusNotificationWatcherReady());
+    log.info("canAppIndicator="+this.canAppIndicator);
+    if (firetray.Utils.prefService.getBoolPref('with_appindicator') &&
+        this.canAppIndicator) {
       /* FIXME: Ubuntu14.04/Unity: successfully closing appind3 crashes FF/TB
        during exit, in Ubuntu's unity-menubar.patch's code.
        https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1393256 */