Issue 3071 - Element Hiding Helper broken in Thunderbird/SeaMonkey Mail

lib/aardvark.js

 /*
  * This Source Code is subject to the terms of the Mozilla Public License
  * version 2.0 (the "License"). You can obtain a copy of the License at
  * http://mozilla.org/MPL/2.0/.
  */
 
 let {Prefs} = require("prefs");
 
 // Make sure to stop selection when we are uninstalled
 onShutdown.add(() => Aardvark.quit());
@@ skipping 574 matching lines @@
     this.boxElem = null;
     E = id => null;
     return false;
   },
 
   select: function(elem)
   {
     if (!elem)
       return false;
 
+    let browser = this.browser;
+    if ("selectedBrowser" in browser)  // tabbrowser element
+      browser = browser.selectedBrowser;
+
     let messageId = ++messageCounter;
     let callback = (message) =>
     {
       let response = message.data;
       if (response.messageId != messageId)
         return;
 
-      this.browser.selectedBrowser.messageManager.removeMessageListener(
+      browser.messageManager.removeMessageListener(
         "ElemHideHelper:GetNodeInfo:Response",
         callback
       );
 
       if (!response.nodeData)
         return;
 
       this.window.openDialog("chrome://elemhidehelper/content/composer.xul",
           "_blank", "chrome,centerscreen,resizable,dialog=no", response);
       this.quit();
     };
 
-    this.browser.selectedBrowser.messageManager.addMessageListener(
+    browser.messageManager.addMessageListener(
       "ElemHideHelper:GetNodeInfo:Response",
       callback
     );
-    this.browser.selectedBrowser.messageManager.sendAsyncMessage(
+    browser.messageManager.sendAsyncMessage(
       "ElemHideHelper:GetNodeInfo",
       messageId,
       {
         element: elem
       }
     );
     return false;
   },
 
   blinkElement: function(elem)
@@ skipping 165 matching lines @@
     // Show help box
     helpBox.showPopup(this.browser, -1, -1, "tooltip", "topleft", "topleft");
     return true;
   }
 }
 
 // Makes sure event handlers like Aardvark.onKeyPress always have the correct
 // this pointer set.
 for (let method of ["onMouseClick", "onMouseScroll", "onKeyPress", "onPageHide", "onMouseMove", "onAfterPaint", "quit"])
   Aardvark[method] = Aardvark[method].bind(Aardvark);