From 7e18b4456321559130082aec7ae3c0fd6a390288 Mon Sep 17 00:00:00 2001
From: Tooru Fujisawa <arai_a@mac.com>
Date: Wed, 18 Nov 2015 20:12:26 +0900
Subject: [PATCH] Bug 1224790 - Use SetFakeModal instead of SetModal for
 non-modal window opened by modal window. r=smaug, mstange

---
 dom/tests/mochitest/bugs/test_bug406375.html  |   4 -
 dom/tests/mochitest/chrome/chrome.ini         |   8 ++
 .../chrome/file_bug1224790-1_modal.xul        |  33 ++++++
 .../chrome/file_bug1224790-1_nonmodal.xul     |  28 +++++
 .../chrome/file_bug1224790-2_modal.xul        |  35 ++++++
 .../chrome/file_bug1224790-2_nonmodal.xul     |  46 ++++++++
 .../mochitest/chrome/test_bug1224790-1.xul    |  58 ++++++++++
 .../mochitest/chrome/test_bug1224790-2.xul    |  59 ++++++++++
 .../windowwatcher/nsWindowWatcher.cpp         |   2 +-
 .../mochitest/tests/SimpleTest/EventUtils.js  | 104 ++++++++++++++++++
 widget/cocoa/nsCocoaWindow.h                  |   3 +
 widget/cocoa/nsCocoaWindow.mm                 |  41 +++++--
 widget/nsIWidget.h                            |  13 ++-
 13 files changed, 415 insertions(+), 19 deletions(-)
 create mode 100644 dom/tests/mochitest/chrome/file_bug1224790-1_modal.xul
 create mode 100644 dom/tests/mochitest/chrome/file_bug1224790-1_nonmodal.xul
 create mode 100644 dom/tests/mochitest/chrome/file_bug1224790-2_modal.xul
 create mode 100644 dom/tests/mochitest/chrome/file_bug1224790-2_nonmodal.xul
 create mode 100644 dom/tests/mochitest/chrome/test_bug1224790-1.xul
 create mode 100644 dom/tests/mochitest/chrome/test_bug1224790-2.xul
diff --git a/dom/tests/mochitest/bugs/test_bug406375.html b/dom/tests/mochitest/bugs/test_bug406375.html
index d0a82af08c9..cd7c9519ebb 100644
--- a/dom/tests/mochitest/bugs/test_bug406375.html
+++ b/dom/tests/mochitest/bugs/test_bug406375.html
@@ -17,10 +17,6 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=406375
 <pre id="test">
 <script type="application/javascript">
 
-if (navigator.platform.startsWith("Mac")) {
-  SimpleTest.expectAssertions(1);
-}
-
 /** Test for Bug 406375 **/
 
 
diff --git a/dom/tests/mochitest/chrome/chrome.ini b/dom/tests/mochitest/chrome/chrome.ini
index c4ca8ee0456..5fcce30cce0 100644
--- a/dom/tests/mochitest/chrome/chrome.ini
+++ b/dom/tests/mochitest/chrome/chrome.ini
@@ -11,6 +11,10 @@ support-files =
   file_bug799299.xul
   file_bug800817.xul
   file_bug830858.xul
+  file_bug1224790-1_modal.xul
+  file_bug1224790-1_nonmodal.xul
+  file_bug1224790-2_modal.xul
+  file_bug1224790-2_nonmodal.xul
   file_subscript_bindings.js
   focus_frameset.html
   focus_window2.xul
@@ -32,6 +36,10 @@ support-files =
 [test_bug800817.xul]
 [test_bug830396.xul]
 [test_bug830858.xul]
+[test_bug1224790-1.xul]
+skip-if = os != 'cocoa'
+[test_bug1224790-2.xul]
+skip-if = os != 'cocoa'
 [test_callback_wrapping.xul]
 [test_clonewrapper.xul]
 [test_cyclecollector.xul]
diff --git a/dom/tests/mochitest/chrome/file_bug1224790-1_modal.xul b/dom/tests/mochitest/chrome/file_bug1224790-1_modal.xul
new file mode 100644
index 00000000000..7a2ad495f0b
--- /dev/null
+++ b/dom/tests/mochitest/chrome/file_bug1224790-1_modal.xul
@@ -0,0 +1,33 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1224790
+-->
+<dialog title="Mozilla Bug 1224790"
+        buttons="accept"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  /** Test for Bug 1224790 **/
+
+  function runTests() {
+    window.openDialog('file_bug1224790-1_nonmodal.xul', '', 'dialog=no');
+  }
+
+  function nonModalClosed() {
+    window.close();
+    opener.wrappedJSObject.modalClosed();
+  }
+
+  SimpleTest.waitForFocus(runTests);
+  ]]>
+  </script>
+</dialog>
diff --git a/dom/tests/mochitest/chrome/file_bug1224790-1_nonmodal.xul b/dom/tests/mochitest/chrome/file_bug1224790-1_nonmodal.xul
new file mode 100644
index 00000000000..e09efc9c0fe
--- /dev/null
+++ b/dom/tests/mochitest/chrome/file_bug1224790-1_nonmodal.xul
@@ -0,0 +1,28 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1224790
+-->
+<window title="Mozilla Bug 1224790"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  /** Test for Bug 1224790 **/
+
+  function runTests() {
+    window.close();
+    opener.wrappedJSObject.nonModalClosed();
+  }
+
+  SimpleTest.waitForFocus(runTests);
+  ]]>
+  </script>
+</window>
diff --git a/dom/tests/mochitest/chrome/file_bug1224790-2_modal.xul b/dom/tests/mochitest/chrome/file_bug1224790-2_modal.xul
new file mode 100644
index 00000000000..34f49e3c4d4
--- /dev/null
+++ b/dom/tests/mochitest/chrome/file_bug1224790-2_modal.xul
@@ -0,0 +1,35 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1224790
+-->
+<dialog title="Mozilla Bug 1224790"
+        buttons="accept"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  /** Test for Bug 1224790 **/
+
+  var nonModal = null;
+
+  function runTests() {
+    nonModal = window.openDialog('file_bug1224790-2_nonmodal.xul', '', 'dialog=no');
+  }
+
+  function nonModalOpened() {
+    window.close();
+    nonModal.wrappedJSObject.modalClosed(opener);
+  }
+
+  SimpleTest.waitForFocus(runTests);
+  ]]>
+  </script>
+</dialog>
diff --git a/dom/tests/mochitest/chrome/file_bug1224790-2_nonmodal.xul b/dom/tests/mochitest/chrome/file_bug1224790-2_nonmodal.xul
new file mode 100644
index 00000000000..0116dfeb26f
--- /dev/null
+++ b/dom/tests/mochitest/chrome/file_bug1224790-2_nonmodal.xul
@@ -0,0 +1,46 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1224790
+-->
+<window title="Mozilla Bug 1224790"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+  /** Test for Bug 1224790 **/
+
+  function runTests() {
+    opener.wrappedJSObject.nonModalOpened()
+  }
+
+  function modalClosed(grandparent) {
+    // Request cycle collection to trigger destructor for parent modal window,
+    // that mutates mAncestorLink of this window.
+    const Ci = Components.interfaces;
+    const Cu = Components.utils;
+    var { Services } = Cu.import("resource://gre/modules/Services.jsm", {});
+    var windowUtils = window.QueryInterface(Ci.nsIInterfaceRequestor).
+      getInterface(Ci.nsIDOMWindowUtils);
+
+    Services.obs.notifyObservers(null, "child-cc-request", null);
+    windowUtils.cycleCollect();
+
+    // Wait for a while.
+    setTimeout(function() {
+      window.close();
+      grandparent.wrappedJSObject.nonModalClosed();
+    }, 3000);
+  }
+
+  SimpleTest.waitForFocus(runTests);
+  ]]>
+  </script>
+</window>
diff --git a/dom/tests/mochitest/chrome/test_bug1224790-1.xul b/dom/tests/mochitest/chrome/test_bug1224790-1.xul
new file mode 100644
index 00000000000..327d2a1741d
--- /dev/null
+++ b/dom/tests/mochitest/chrome/test_bug1224790-1.xul
@@ -0,0 +1,58 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1224790
+-->
+<window title="Mozilla Bug 1224790"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+
+  /** Test for Bug 1224790 **/
+  /*
+   * 1. Opens modal dialog
+   * 2. Open non-modal window from modal dialog
+   * 3. Close non-modal window
+   * 4. Close modal dialog
+   * 5. Click button to ensure mouse event is working
+   */
+
+  function startTest() {
+    window.openDialog('file_bug1224790-1_modal.xul', '', 'modal');
+  }
+
+  function modalClosed() {
+    SimpleTest.waitForFocus(gotFocus);
+  }
+
+  function gotFocus() {
+    var button = document.getElementById('button');
+    synthesizeMouseAtCenter(button, { type: 'mousemove' }, window);
+    // The bug is not reproducible with synthesizeMouseAtCenter.
+    // Need to emulate native mouse event.
+    synthesizeNativeOSXClick(button.boxObject.screenX + button.boxObject.width / 2,
+                             button.boxObject.screenY + button.boxObject.height / 2);
+  }
+
+  function onClick() {
+    ok(true, "Click event should be fired");
+    SimpleTest.finish();
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  SimpleTest.waitForFocus(startTest);
+  ]]>
+  </script>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1224790"
+     target="_blank">Mozilla Bug 1224790</a>
+  </body>
+  <button id="button" label="button" oncommand="onClick()" />
+</window>
diff --git a/dom/tests/mochitest/chrome/test_bug1224790-2.xul b/dom/tests/mochitest/chrome/test_bug1224790-2.xul
new file mode 100644
index 00000000000..97187ac13ab
--- /dev/null
+++ b/dom/tests/mochitest/chrome/test_bug1224790-2.xul
@@ -0,0 +1,59 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1224790
+-->
+<window title="Mozilla Bug 1224790"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"/>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"/>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+
+  /** Test for Bug 1224790 **/
+  /*
+   * 1. Opens modal dialog
+   * 2. Open non-modal window from modal dialog
+   * 3. Close modal dialog
+   * 4. Wait for a while for destructor for modal dialog
+   * 5. Close non-modal window
+   * 6. Click button to ensure mouse event is working
+   */
+
+  function startTest() {
+    window.openDialog('file_bug1224790-2_modal.xul', '', 'modal');
+  }
+
+  function nonModalClosed() {
+    SimpleTest.waitForFocus(gotFocus);
+  }
+
+  function gotFocus() {
+    var button = document.getElementById('button');
+    synthesizeMouseAtCenter(button, { type: 'mousemove' }, window);
+    // The bug is not reproducible with synthesizeMouseAtCenter.
+    // Need to emulate native mouse event.
+    synthesizeNativeOSXClick(button.boxObject.screenX + button.boxObject.width / 2,
+                             button.boxObject.screenY + button.boxObject.height / 2);
+  }
+
+  function onClick() {
+    ok(true, "Click event should be fired");
+    SimpleTest.finish();
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  SimpleTest.waitForFocus(startTest);
+  ]]>
+  </script>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1224790"
+     target="_blank">Mozilla Bug 1224790</a>
+  </body>
+  <button id="button" label="button" oncommand="onClick()" />
+</window>
diff --git a/embedding/components/windowwatcher/nsWindowWatcher.cpp b/embedding/components/windowwatcher/nsWindowWatcher.cpp
index a7b1a1e511e..a6520624798 100644
--- a/embedding/components/windowwatcher/nsWindowWatcher.cpp
+++ b/embedding/components/windowwatcher/nsWindowWatcher.cpp
@@ -1053,7 +1053,7 @@ nsWindowWatcher::OpenWindowInternal(nsIDOMWindow* aParent,
         nsCOMPtr<nsIWidget> parentWidget;
         parentWindow->GetMainWidget(getter_AddRefs(parentWidget));
         if (parentWidget) {
-          parentWidget->SetModal(true);
+          parentWidget->SetFakeModal(true);
         }
       }
     } else {
diff --git a/testing/mochitest/tests/SimpleTest/EventUtils.js b/testing/mochitest/tests/SimpleTest/EventUtils.js
index 42ca85ecb35..8f35605b993 100644
--- a/testing/mochitest/tests/SimpleTest/EventUtils.js
+++ b/testing/mochitest/tests/SimpleTest/EventUtils.js
@@ -15,6 +15,7 @@
  *  synthesizeNativeKey
  *  synthesizeMouseExpectEvent
  *  synthesizeKeyExpectEvent
+ *  synthesizeNativeClick
  *
  *  When adding methods to this file, please add a performance test for it.
  */
@@ -36,6 +37,11 @@ window.__defineGetter__('_EU_Cc', function() {
   return c.value && !c.writable ? Components.classes : SpecialPowers.Cc;
 });
 
+window.__defineGetter__('_EU_Cu', function() {
+  var c = Object.getOwnPropertyDescriptor(window, 'Components');
+  return c.value && !c.writable ? Components.utils : SpecialPowers.Cu;
+});
+
 /**
  * Send a mouse event to the node aTarget (aTarget can be an id, or an
  * actual node) . The "event" passed in to aEvent is just a JavaScript
@@ -1501,3 +1507,101 @@ function synthesizeSelectionSet(aOffset, aLength, aReverse, aWindow)
   var flags = aReverse ? SELECTION_SET_FLAG_REVERSE : 0;
   return utils.sendSelectionSetEvent(aOffset, aLength, flags);
 }
+
+/*
+ * Synthesize a native mouse click event at a particular point in screen.
+ * This function should be used only for testing native event loop.
+ * Use synthesizeMouse instead for most case.
+ *
+ * This works only on OS X.  Throws an error on other OS.  Also throws an error
+ * when the library or any of function are not found, or something goes wrong
+ * in native functions.
+ */
+function synthesizeNativeOSXClick(x, y)
+{
+  var { ctypes } = _EU_Cu.import("resource://gre/modules/ctypes.jsm", {});
+
+  // Library
+  var CoreFoundation = ctypes.open("/System/Library/Frameworks/CoreFoundation.framework/CoreFoundation");
+  var CoreGraphics = ctypes.open("/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics");
+
+  // Contants
+  var kCGEventLeftMouseDown = 1;
+  var kCGEventLeftMouseUp = 2;
+  var kCGEventSourceStateHIDSystemState = 1;
+  var kCGHIDEventTap = 0;
+  var kCGMouseButtonLeft = 0;
+  var kCGMouseEventClickState = 1;
+
+  // Types
+  var CGEventField = ctypes.uint32_t;
+  var CGEventRef = ctypes.voidptr_t;
+  var CGEventSourceRef = ctypes.voidptr_t;
+  var CGEventSourceStateID = ctypes.uint32_t;
+  var CGEventTapLocation = ctypes.uint32_t;
+  var CGEventType = ctypes.uint32_t;
+  var CGFloat = ctypes.voidptr_t.size == 4 ? ctypes.float : ctypes.double;
+  var CGMouseButton = ctypes.uint32_t;
+
+  var CGPoint = new ctypes.StructType(
+    "CGPoint",
+    [ { "x" : CGFloat },
+      { "y" : CGFloat } ]);
+
+  // Functions
+  var CGEventSourceCreate = CoreGraphics.declare(
+    "CGEventSourceCreate",
+    ctypes.default_abi,
+    CGEventSourceRef, CGEventSourceStateID);
+  var CGEventCreateMouseEvent = CoreGraphics.declare(
+    "CGEventCreateMouseEvent",
+    ctypes.default_abi,
+    CGEventRef,
+    CGEventSourceRef, CGEventType, CGPoint, CGMouseButton);
+  var CGEventSetIntegerValueField = CoreGraphics.declare(
+    "CGEventSetIntegerValueField",
+    ctypes.default_abi,
+    ctypes.void_t,
+    CGEventRef, CGEventField, ctypes.int64_t);
+  var CGEventPost = CoreGraphics.declare(
+    "CGEventPost",
+    ctypes.default_abi,
+    ctypes.void_t,
+    CGEventTapLocation, CGEventRef);
+  var CFRelease = CoreFoundation.declare(
+    "CFRelease",
+    ctypes.default_abi,
+    ctypes.void_t,
+    CGEventRef);
+
+  var source = CGEventSourceCreate(kCGEventSourceStateHIDSystemState);
+  if (!source) {
+    throw new Error("CGEventSourceCreate returns null");
+  }
+
+  var loc = new CGPoint({ x: x, y: y });
+  var event = CGEventCreateMouseEvent(source, kCGEventLeftMouseDown, loc,
+                                      kCGMouseButtonLeft);
+  if (!event) {
+    throw new Error("CGEventCreateMouseEvent returns null");
+  }
+  CGEventSetIntegerValueField(event, kCGMouseEventClickState,
+                              new ctypes.Int64(1));
+  CGEventPost(kCGHIDEventTap, event);
+  CFRelease(event);
+
+  event = CGEventCreateMouseEvent(source, kCGEventLeftMouseUp, loc,
+                                      kCGMouseButtonLeft);
+  if (!event) {
+    throw new Error("CGEventCreateMouseEvent returns null");
+  }
+  CGEventSetIntegerValueField(event, kCGMouseEventClickState,
+                              new ctypes.Int64(1));
+  CGEventPost(kCGHIDEventTap, event);
+  CFRelease(event);
+
+  CFRelease(source);
+
+  CoreFoundation.close();
+  CoreGraphics.close();
+}
diff --git a/widget/cocoa/nsCocoaWindow.h b/widget/cocoa/nsCocoaWindow.h
index 930f3a77567..acd0db0639c 100644
--- a/widget/cocoa/nsCocoaWindow.h
+++ b/widget/cocoa/nsCocoaWindow.h
@@ -268,6 +268,7 @@ public:
     NS_IMETHOD              Enable(bool aState) override;
     virtual bool            IsEnabled() const override;
     NS_IMETHOD              SetModal(bool aState) override;
+    NS_IMETHOD              SetFakeModal(bool aState) override;
     virtual bool            IsVisible() const override;
     NS_IMETHOD              SetFocus(bool aState=false) override;
     virtual LayoutDeviceIntPoint WidgetToScreenOffset() override;
@@ -417,6 +418,7 @@ protected:
                      const IMENotification& aIMENotification) override;
 
   nsIWidget*           mParent;         // if we're a popup, this is our parent [WEAK]
+  nsIWidget*           mAncestorLink;   // link to traverse ancestors [WEAK]
   BaseWindow*          mWindow;         // our cocoa window [STRONG]
   WindowDelegate*      mDelegate;       // our delegate for processing window msgs [STRONG]
   RefPtr<nsMenuBarX> mMenuBar;
@@ -438,6 +440,7 @@ protected:
   bool                 mInFullScreenTransition; // true from the request to enter/exit fullscreen
                                                 // (MakeFullScreen() call) to EnteredFullScreen()
   bool                 mModal;
+  bool                 mFakeModal;
 
   // Only true on 10.7+ if SetShowsFullScreenButton(true) is called.
   bool                 mSupportsNativeFullScreen;
diff --git a/widget/cocoa/nsCocoaWindow.mm b/widget/cocoa/nsCocoaWindow.mm
index 6df829df6fe..5adf27fd87d 100644
--- a/widget/cocoa/nsCocoaWindow.mm
+++ b/widget/cocoa/nsCocoaWindow.mm
@@ -99,6 +99,7 @@ static void RollUpPopups()
 
 nsCocoaWindow::nsCocoaWindow()
 : mParent(nullptr)
+, mAncestorLink(nullptr)
 , mWindow(nil)
 , mDelegate(nil)
 , mSheetWindowParent(nil)
@@ -112,6 +113,7 @@ nsCocoaWindow::nsCocoaWindow()
 , mInFullScreenMode(false)
 , mInFullScreenTransition(false)
 , mModal(false)
+, mFakeModal(false)
 , mSupportsNativeFullScreen(false)
 , mInNativeFullScreenMode(false)
 , mIsAnimationSuppressed(false)
@@ -157,6 +159,7 @@ nsCocoaWindow::~nsCocoaWindow()
     } else {
       nsCocoaWindow* childWindow = static_cast<nsCocoaWindow*>(kid);
       childWindow->mParent = nullptr;
+      childWindow->mAncestorLink = mAncestorLink;
       kid = kid->GetPrevSibling();
     }
   }
@@ -271,6 +274,7 @@ nsresult nsCocoaWindow::Create(nsIWidget *aParent,
   Inherited::BaseCreate(aParent, newBounds, aInitData);
 
   mParent = aParent;
+  mAncestorLink = aParent;
 
   // Applications that use native popups don't want us to create popup windows.
   if ((mWindowType == eWindowType_popup) && UseNativePopupWindows())
@@ -505,6 +509,13 @@ NS_IMETHODIMP nsCocoaWindow::Destroy()
     return NS_OK;
   mOnDestroyCalled = true;
 
+  // SetFakeModal(true) is called for non-modal window opened by modal window.
+  // On Cocoa, it needs corresponding SetFakeModal(false) on destroy to restore
+  // ancestor windows' state.
+  if (mFakeModal) {
+    SetFakeModal(false);
+  }
+
   // If we don't hide here we run into problems with panels, this is not ideal.
   // (Bug 891424)
   Show(false);
@@ -604,7 +615,7 @@ NS_IMETHODIMP nsCocoaWindow::SetModal(bool aState)
   nsAutoreleasePool localPool;
 
   mModal = aState;
-  nsCocoaWindow *aParent = static_cast<nsCocoaWindow*>(mParent);
+  nsCocoaWindow *ancestor = static_cast<nsCocoaWindow*>(mAncestorLink);
   if (aState) {
     ++gXULModalLevel;
     // When a non-sheet window gets "set modal", make the window(s) that it
@@ -615,16 +626,16 @@ NS_IMETHODIMP nsCocoaWindow::SetModal(bool aState)
     // ShowModal() (each of these event loops is "exclusive", and can't run at
     // the same time as other (similar) event loops).
     if (mWindowType != eWindowType_sheet) {
-      while (aParent) {
-        if (aParent->mNumModalDescendents++ == 0) {
-          NSWindow *aWindow = aParent->GetCocoaWindow();
-          if (aParent->mWindowType != eWindowType_invisible) {
+      while (ancestor) {
+        if (ancestor->mNumModalDescendents++ == 0) {
+          NSWindow *aWindow = ancestor->GetCocoaWindow();
+          if (ancestor->mWindowType != eWindowType_invisible) {
             [[aWindow standardWindowButton:NSWindowCloseButton] setEnabled:NO];
             [[aWindow standardWindowButton:NSWindowMiniaturizeButton] setEnabled:NO];
             [[aWindow standardWindowButton:NSWindowZoomButton] setEnabled:NO];
           }
         }
-        aParent = static_cast<nsCocoaWindow*>(aParent->mParent);
+        ancestor = static_cast<nsCocoaWindow*>(ancestor->mParent);
       }
       [mWindow setLevel:NSModalPanelWindowLevel];
       nsCocoaWindowList *windowList = new nsCocoaWindowList;
@@ -639,17 +650,17 @@ NS_IMETHODIMP nsCocoaWindow::SetModal(bool aState)
     --gXULModalLevel;
     NS_ASSERTION(gXULModalLevel >= 0, "Mismatched call to nsCocoaWindow::SetModal(false)!");
     if (mWindowType != eWindowType_sheet) {
-      while (aParent) {
-        if (--aParent->mNumModalDescendents == 0) {
-          NSWindow *aWindow = aParent->GetCocoaWindow();
-          if (aParent->mWindowType != eWindowType_invisible) {
+      while (ancestor) {
+        if (--ancestor->mNumModalDescendents == 0) {
+          NSWindow *aWindow = ancestor->GetCocoaWindow();
+          if (ancestor->mWindowType != eWindowType_invisible) {
             [[aWindow standardWindowButton:NSWindowCloseButton] setEnabled:YES];
             [[aWindow standardWindowButton:NSWindowMiniaturizeButton] setEnabled:YES];
             [[aWindow standardWindowButton:NSWindowZoomButton] setEnabled:YES];
           }
         }
-        NS_ASSERTION(aParent->mNumModalDescendents >= 0, "Widget hierarchy changed while modal!");
-        aParent = static_cast<nsCocoaWindow*>(aParent->mParent);
+        NS_ASSERTION(ancestor->mNumModalDescendents >= 0, "Widget hierarchy changed while modal!");
+        ancestor = static_cast<nsCocoaWindow*>(ancestor->mParent);
       }
       if (gGeckoAppModalWindowList) {
         NS_ASSERTION(gGeckoAppModalWindowList->window == this, "Widget hierarchy changed while modal!");
@@ -666,6 +677,12 @@ NS_IMETHODIMP nsCocoaWindow::SetModal(bool aState)
   return NS_OK;
 }
 
+NS_IMETHODIMP nsCocoaWindow::SetFakeModal(bool aState)
+{
+    mFakeModal = aState;
+    return SetModal(aState);
+}
+
 // Hide or show this window
 NS_IMETHODIMP nsCocoaWindow::Show(bool bState)
 {
diff --git a/widget/nsIWidget.h b/widget/nsIWidget.h
index 12a92ece8fd..0584e6c96ad 100644
--- a/widget/nsIWidget.h
+++ b/widget/nsIWidget.h
@@ -123,8 +123,8 @@ typedef void* nsNativeWidget;
 #endif
 
 #define NS_IWIDGET_IID \
-{ 0x7b736a0c, 0x2262, 0x4f37, \
-  { 0xbd, 0xed, 0xe5, 0x60, 0x88, 0x1c, 0x36, 0xdd } }
+{ 0xd953b7a1, 0x6981, 0x4ed7, \
+  { 0xbc, 0xf0, 0xed, 0x96, 0x70, 0xee, 0x23, 0x28 } }
 
 /*
  * Window shadow styles
@@ -594,6 +594,15 @@ class nsIWidget : public nsISupports {
      */
     NS_IMETHOD SetModal(bool aModal) = 0;
 
+    /**
+     * Make the non-modal window opened by modal window fake-modal, that will
+     * call SetFakeModal(false) on destroy on Cocoa.
+     */
+    NS_IMETHOD SetFakeModal(bool aModal)
+    {
+        return SetModal(aModal);
+    }
+
     /**
      * The maximum number of simultaneous touch contacts supported by the device.
      * In the case of devices with multiple digitizers (e.g. multiple touch screens),
