Fixed: EHH - Filter creating window won't close

chrome/content/composer.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");
 
 let domainData;
 let nodeData;
@@ skipping 117 matching lines @@
 }
 
 /*********************
  * General functions *
  *********************/
 
 function init() {
   var element = window.arguments[0];
   doc = element.ownerDocument;
   var wnd = doc.defaultView;
-  wnd.addEventListener("unload", function(event){ togglePreview(false); }, true);

[Wladimir Palant, 2012/11/08 10:42:34]

So togglePreview() is the issue? Then this is the wrong solution.

1) We are cleaning up when the window unloads - that's pointless, nobody will
see that window.
2) Adding an "unload" event listener has the side-effect of disabling fast
back&forward for that page.

How about checking wnd.closed in togglePreview()?

[Andrey Novikov, 2012/11/08 10:54:54]

Exact issue is that previewStyle is dead object after reload. I can not check
wnd.closed because it's not closed, it was jast reloaded. Any other way to hook
reload event? I've tried document.unload but it didn't fire. 

 
   // Check whether element hiding group is disabled
   let subscription = AdblockPlus.getSubscription("~eh~");
   if (subscription && subscription.disabled)
   {
     let warning = document.getElementById("groupDisabledWarning");
     if (/\?1\?/.test(warning.textContent))
       warning.textContent = warning.textContent.replace(/\?1\?/g, subscription.title);
     warning.hidden = false;
   }
@@ skipping 400 matching lines @@
 function togglePreview(preview) {
   if (preview) {
     if (!previewStyle || !previewStyle.parentNode) {
       previewStyle = doc.createElementNS("http://www.w3.org/1999/xhtml", "style");
       previewStyle.setAttribute("type", "text/css");
       doc.documentElement.appendChild(previewStyle);
     }
     previewStyle.textContent = stylesheetData;
   }
   else {
-    if (previewStyle && previewStyle.parentNode)
-      previewStyle.parentNode.removeChild(previewStyle);
+    try
+    {
+      if (previewStyle && previewStyle.parentNode)
+        previewStyle.parentNode.removeChild(previewStyle);
+    }
+    catch (e)
+    {
+      // if the window was closed (reloaded) we end up with dead object reference
+      // https://bugzilla.mozilla.org/show_bug.cgi?id=695480
+      // just ignore this case
+    }
     previewStyle = null;
   }
 }
 
 function changeDomain(node) {
   domainData.selected = node.getAttribute("value");
   updateExpression();
 }
 
 function toggleAttr(node) {
@@ skipping 56 matching lines @@
 
   fillAttributes(item.nodeData);
 }
 
 function addExpression()
 {
   AdblockPlus.addPatterns([document.getElementById("expression").value]);
 
   togglePreview(false);
 }