Issue 3223 - Implement context menu fallback for SeaMonkey Mail and Thunderbird

lib/ui.js

Index: lib/ui.js
===================================================================
--- a/lib/ui.js
+++ b/lib/ui.js
@@ -1595,24 +1595,33 @@ let UI = exports.UI =
 
   /**
    * Adds Adblock Plus menu items to the content area context menu when it shows
    * up.
    */
   fillContentContextMenu: function(/**Element*/ popup)
   {
     let window = popup.ownerDocument.defaultView;
-    if (!window.gContextMenuContentData ||
-      typeof window.gContextMenuContentData.addonInfo != "object" ||
-      typeof window.gContextMenuContentData.addonInfo.adblockplus != "object")
+    let data = window.gContextMenuContentData;
+    if (!data)
     {
-      return;
+      // This is SeaMonkey Mail or Thunderbird, they won't get context menu data
+      // for us. Send the notification ourselves.
+      data = {
+        event: {target: popup.triggerNode},
+        addonInfo: {},
+        get wrappedJSObject() {return this;}
+      };
+      Services.obs.notifyObservers(data, "AdblockPlus:content-contextmenu", null);
     }
 
-    let items = window.gContextMenuContentData.addonInfo.adblockplus;
+    if (typeof data.addonInfo != "object" || typeof data.addonInfo.adblockplus != "object")
+      return;
+
+    let items = data.addonInfo.adblockplus;
     let clicked = null;
     let menuItems = [];
 
     function menuItemTriggered(id, nodeData)
     {
       clicked = id;
       this.blockItem(window, id, nodeData);
     }