diff -r 000000000000 -r 6474c204b198 browser/base/content/test/general/browser_tab_drag_drop_perwindow.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/general/browser_tab_drag_drop_perwindow.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,50 @@
+/* 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/. */
+
+function test() {
+  //initialization
+  waitForExplicitFinish();
+
+  let scriptLoader = Cc["@mozilla.org/moz/jssubscript-loader;1"].
+                     getService(Ci.mozIJSSubScriptLoader);
+  let ChromeUtils = {};
+  scriptLoader.loadSubScript("chrome://mochikit/content/tests/SimpleTest/ChromeUtils.js", ChromeUtils);
+
+  function testOnWindow(aIsPrivate, aCallback) {
+    whenNewWindowLoaded({private: aIsPrivate}, function(win) {
+      executeSoon(function() aCallback(win));
+    });
+  }
+
+  testOnWindow(false, function(aNormalWindow) {
+    testOnWindow(true, function(aPrivateWindow) {
+      // Open a tab in each window
+      let normalTab = aNormalWindow.gBrowser.addTab("about:blank", {skipAnimation: true});
+      let privateTab = aPrivateWindow.gBrowser.addTab("about:blank", {skipAnimation: true});
+
+      let effect = ChromeUtils.synthesizeDrop(normalTab, privateTab,
+        [[{type: TAB_DROP_TYPE, data: normalTab}]],
+        null, aNormalWindow, aPrivateWindow);
+      is(effect, "none", "Should not be able to drag a normal tab to a private window");
+
+      effect = ChromeUtils.synthesizeDrop(privateTab, normalTab,
+        [[{type: TAB_DROP_TYPE, data: privateTab}]],
+        null, aPrivateWindow, aNormalWindow);
+      is(effect, "none", "Should not be able to drag a private tab to a normal window");
+
+      aNormalWindow.gBrowser.swapBrowsersAndCloseOther(normalTab, privateTab);
+      is(aNormalWindow.gBrowser.tabs.length, 2, "Prevent moving a normal tab to a private tabbrowser");
+      is(aPrivateWindow.gBrowser.tabs.length, 2, "Prevent accepting a normal tab in a private tabbrowser");
+
+      aPrivateWindow.gBrowser.swapBrowsersAndCloseOther(privateTab, normalTab);
+      is(aPrivateWindow.gBrowser.tabs.length, 2, "Prevent moving a private tab to a normal tabbrowser");
+      is(aNormalWindow.gBrowser.tabs.length, 2, "Prevent accepting a private tab in a normal tabbrowser");
+
+      aNormalWindow.close();
+      aPrivateWindow.close();
+      finish();
+    });
+  });
+}
+