--- a/toolkit/content/tests/chrome/bug263683_window.xul
+++ b/toolkit/content/tests/chrome/bug263683_window.xul
@@ -8,204 +8,18 @@
 <?xml-stylesheet
   href="chrome://mochikit/content/tests/SimpleTest/test.css"
   type="text/css"?>
 
 <window id="263683test"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         width="600"
         height="600"
-        onload="SimpleTest.executeSoon(startTest);"
+        onload="window.opener.SimpleTest.executeSoon(startTest);"
         title="263683 test">
 
   <script type="application/javascript"><![CDATA[
-    ChromeUtils.import("resource://gre/modules/AppConstants.jsm");
-    ChromeUtils.import("resource://testing-common/BrowserTestUtils.jsm");
-    ChromeUtils.import("resource://testing-common/ContentTask.jsm");
-    ContentTask.setTestScope(window.opener.wrappedJSObject);
-
-    var gPrefsvc = Cc["@mozilla.org/preferences-service;1"].getService(Ci.nsIPrefBranch);
-    var gFindBar = null;
-    var gBrowser;
-
-    var imports = ["SimpleTest", "ok", "info", "is"];
-    for (var name of imports) {
-      window[name] = window.opener.wrappedJSObject[name];
-    }
-
     function startTest() {
-      (async function() {
-        gFindBar = document.getElementById("FindToolbar");
-        // Testing on a remote browser has been disabled due to frequent
-        // intermittent failures.
-        for (let browserId of ["content"/*, "content-remote"*/]) {
-          await startTestWithBrowser(browserId);
-        }
-      })().then(() => {
-        window.close();
-        SimpleTest.finish();
-      });
-    }
-
-    async function startTestWithBrowser(browserId) {
-      // We're bailing out when testing a remote browser on OSX 10.6, because it
-      // fails permanently.
-      if (browserId.endsWith("remote") && AppConstants.isPlatformAndVersionAtMost("macosx", 11)) {
-        return;
-      }
-
-      info("Starting test with browser '" + browserId + "'");
-      gBrowser = document.getElementById(browserId);
-      gFindBar.browser = gBrowser;
-      let promise = BrowserTestUtils.browserLoaded(gBrowser);
-      gBrowser.loadURI('data:text/html,<h2>Text mozilla</h2><input id="inp" type="text" />');
-      await promise;
-      await onDocumentLoaded();
-    }
-
-    function toggleHighlightAndWait(highlight) {
-      return new Promise(resolve => {
-        let listener = {
-          onHighlightFinished: function() {
-            gFindBar.browser.finder.removeResultListener(listener);
-            resolve();
-          }
-        };
-        gFindBar.browser.finder.addResultListener(listener);
-        gFindBar.toggleHighlight(highlight);
-      });
-    }
-
-    async function onDocumentLoaded() {
-      gFindBar.open();
-      var search = "mozilla";
-      gFindBar._findField.focus();
-      gFindBar._findField.value = search;
-      var matchCase = gFindBar.getElement("find-case-sensitive");
-      if (matchCase.checked) {
-        matchCase.doCommand();
-      }
-
-      let promise = toggleHighlightAndWait(true);
-      gFindBar._find();
-      await promise;
-
-      await ContentTask.spawn(gBrowser, { search }, async function(args) {
-        let controller = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
-                                 .getInterface(Ci.nsISelectionDisplay)
-                                 .QueryInterface(Ci.nsISelectionController);
-        Assert.ok("SELECTION_FIND" in controller, "Correctly detects new selection type");
-        let selection = controller.getSelection(controller.SELECTION_FIND);
-
-        Assert.equal(selection.rangeCount, 1,
-          "Correctly added a match to the selection type");
-        Assert.equal(selection.getRangeAt(0).toString().toLowerCase(),
-          args.search, "Added the correct match");
-      });
-
-      await toggleHighlightAndWait(false);
-
-      await ContentTask.spawn(gBrowser, { search }, async function(args) {
-        let controller = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
-                                 .getInterface(Ci.nsISelectionDisplay)
-                                 .QueryInterface(Ci.nsISelectionController);
-        let selection = controller.getSelection(controller.SELECTION_FIND);
-        Assert.equal(selection.rangeCount, 0, "Correctly removed the range");
-
-        let input = content.document.getElementById("inp");
-        input.value = args.search;
-      });
- 
-      await toggleHighlightAndWait(true);
-
-      await ContentTask.spawn(gBrowser, { search }, async function(args) {
-        let input = content.document.getElementById("inp");
-        let inputController = input.editor.selectionController;
-        let inputSelection = inputController.getSelection(inputController.SELECTION_FIND);
-
-        Assert.equal(inputSelection.rangeCount, 1,
-          "Correctly added a match from input to the selection type");
-        Assert.equal(inputSelection.getRangeAt(0).toString().toLowerCase(),
-          args.search, "Added the correct match");
-      });
-
-      await toggleHighlightAndWait(false);
-
-      await ContentTask.spawn(gBrowser, null, async function() {
-        let input = content.document.getElementById("inp");
-        let inputController = input.editor.selectionController;
-        let inputSelection = inputController.getSelection(inputController.SELECTION_FIND);
-
-        Assert.equal(inputSelection.rangeCount, 0, "Correctly removed the range");
-      });
-
-      // For posterity, test iframes too.
-
-      promise = BrowserTestUtils.browserLoaded(gBrowser);
-      gBrowser.loadURI('data:text/html,<h2>Text mozilla</h2><iframe id="leframe" ' +
-        'src="data:text/html,Text mozilla"></iframe>');
-      await promise;
-
-      await toggleHighlightAndWait(true);
-
-      await ContentTask.spawn(gBrowser, { search }, async function(args) {
-        function getSelection(docShell) {
-          let controller = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
-                                   .getInterface(Ci.nsISelectionDisplay)
-                                   .QueryInterface(Ci.nsISelectionController);
-          return controller.getSelection(controller.SELECTION_FIND);
-        }
-
-        let selection = getSelection(docShell);
-        Assert.equal(selection.rangeCount, 1,
-          "Correctly added a match to the selection type");
-        Assert.equal(selection.getRangeAt(0).toString().toLowerCase(),
-          args.search, "Added the correct match");
-
-        // Check the iframe too:
-        let frame = content.document.getElementById("leframe");
-        // Hoops! Get the docShell first, then the selection.
-        selection = getSelection(frame.contentWindow
-          .QueryInterface(Ci.nsIInterfaceRequestor)
-          .getInterface(Ci.nsIWebNavigation)
-          .QueryInterface(Ci.nsIDocShell));
-        Assert.equal(selection.rangeCount, 1,
-          "Correctly added a match to the selection type");
-        Assert.equal(selection.getRangeAt(0).toString().toLowerCase(),
-          args.search, "Added the correct match");
-      });
-
-      await toggleHighlightAndWait(false);
-
-      let matches = gFindBar._foundMatches.value.match(/([\d]*)\sof\s([\d]*)/);
-      is(matches[1], "2", "Found correct amount of matches")
-
-      await ContentTask.spawn(gBrowser, null, async function(args) {
-        function getSelection(docShell) {
-          let controller = docShell.QueryInterface(Ci.nsIInterfaceRequestor)
-                                   .getInterface(Ci.nsISelectionDisplay)
-                                   .QueryInterface(Ci.nsISelectionController);
-          return controller.getSelection(controller.SELECTION_FIND);
-        }
-
-        let selection = getSelection(docShell);
-        Assert.equal(selection.rangeCount, 0, "Correctly removed the range");
-
-        // Check the iframe too:
-        let frame = content.document.getElementById("leframe");
-        // Hoops! Get the docShell first, then the selection.
-        selection = getSelection(frame.contentWindow
-          .QueryInterface(Ci.nsIInterfaceRequestor)
-          .getInterface(Ci.nsIWebNavigation)
-          .QueryInterface(Ci.nsIDocShell));
-        Assert.equal(selection.rangeCount, 0, "Correctly removed the range");
-
-        content.document.documentElement.focus();
-      });
-
-      gFindBar.close(true);
+      window.opener.SimpleTest.ok(true);
+      window.opener.SimpleTest.finish();
     }
   ]]></script>
-
-  <browser type="content" primary="true" flex="1" id="content" src="about:blank"/>
-  <browser type="content" primary="true" flex="1" id="content-remote" remote="true" src="about:blank"/>
-  <findbar id="FindToolbar" browserid="content"/>
 </window>

--- a/toolkit/content/widgets/general.js
+++ b/toolkit/content/widgets/general.js
@@ -1,17 +1,41 @@
 /* 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/. */
 
 "use strict";
 
 {
 
+  let windowID = Math.random();
+  let unloaded = false;
+  console.log("general.js: loaded", windowID, window.location.toString())
+window.addEventListener("unload", () => {
+  unloaded = true;
+  console.log("general.js: window unload fired", windowID);
+}, { once: true });
+
+let i = 0;
 class MozDeck extends MozXULElement {
+  constructor() {
+    super();
+    this.i = i++;
+    console.log("general.js: MozDeck constructor", this.i, windowID);
+  }
+  connectedCallback() {
+    console.log("general.js: MozDeck connectedCallback", this.i, windowID, unloaded);
+    if (unloaded) {
+      console.log("general.js: MozDeck running script after unload", this.parentNode.outerHTML);
+    }
+  }
+  disconnectedCallback() {
+    console.log("general.js: MozDeck disconnectedCallback", this.i, windowID);
+  }
+
   set selectedIndex(val) {
     if (this.selectedIndex == val) return val;
     this.setAttribute("selectedIndex", val);
     var event = document.createEvent("Events");
     event.initEvent("select", true, true);
     this.dispatchEvent(event);
     return val;
   }