Backed out changeset 09ccf334001b (bug 1592416) for causing bug 1640077 to fail.

layout/xul/nsMenuPopupFrame.cpp

@@ -245,8 +245,8 @@ nsPopupLevel nsMenuPopupFrame::PopupLevel(bool aIsNoAutoHide) const {
 
 void nsMenuPopupFrame::EnsureWidget(bool aRecreate) {
   nsView* ourView = GetView();
-  auto* widget = GetWidget();
-  if (aRecreate || (widget && widget->NeedsRecreateToReshow())) {
+  if (aRecreate) {
+    auto* widget = GetWidget();
     if (widget) {
       // Widget's WebRender resources needs to be cleared before creating new
       // widget.

widget/cocoa/nsCocoaWindow.h

@@ -226,8 +226,6 @@ class nsCocoaWindow final : public nsBaseWidget, public nsPIWidgetCocoa {
   virtual void Destroy() override;
 
   virtual void Show(bool aState) override;
-  virtual bool NeedsRecreateToReshow() override;
-
   virtual nsIWidget* GetSheetWindowParent(void) override;
   virtual void Enable(bool aState) override;
   virtual bool IsEnabled() const override;

widget/cocoa/nsCocoaWindow.mm

@@ -487,14 +487,6 @@ nsresult nsCocoaWindow::CreateNativeWindow(const NSRect& aRect, nsBorderStyle aB
     SetPopupWindowLevel();
     [mWindow setBackgroundColor:[NSColor clearColor]];
     [mWindow setOpaque:NO];
-
-    // When multiple spaces are in use and the browser is assigned to a
-    // particular space, override the "Assign To" space and display popups on
-    // the active space. Does not work with multiple displays. See
-    // NeedsRecreateToReshow() for multi-display with multi-space workaround.
-    NSWindowCollectionBehavior behavior = [mWindow collectionBehavior];
-    behavior |= NSWindowCollectionBehaviorMoveToActiveSpace;
-    [mWindow setCollectionBehavior:behavior];
   } else {
     // Make sure that regular windows are opaque from the start, so that
     // nsChildView::WidgetTypeSupportsAcceleration returns true for them.
@@ -965,17 +957,6 @@ void nsCocoaWindow::Show(bool bState) {
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }
 
-// Work around a problem where with multiple displays and multiple spaces
-// enabled, where the browser is assigned to a single display or space, popup
-// windows that are reshown after being hidden with [NSWindow orderOut] show on
-// the assigned space even when opened from another display. Apply the
-// workaround whenever more than one display is enabled.
-bool nsCocoaWindow::NeedsRecreateToReshow() {
-  // Limit the workaround to popup windows because only they need to override
-  // the "Assign To" setting. i.e., to display where the parent window is.
-  return (mWindowType == eWindowType_popup) && ([[NSScreen screens] count] > 1);
-}
-
 struct ShadowParams {
   float standardDeviation;
   float density;

widget/nsIWidget.h

@@ -647,12 +647,6 @@ class nsIWidget : public nsISupports {
    */
   virtual void Show(bool aState) = 0;
 
-  /**
-   * Whether or not a widget must be recreated after being hidden to show
-   * again properly.
-   */
-  virtual bool NeedsRecreateToReshow() { return false; }
-
   /**
    * Make the window modal.
    */