Bug 1665456 - Ensure window focus received for skele UI window r=mhowell

Because we create our initial window much earlier, we do not receive the
initial activation and focus messages in the same way. Accordingly, we
need to refocus the window once everything is properly set up to handle
it.

Regarding testing, the intent is that this will be covered by existing
tests, since this is not intended to be a behavioral change for window
focus. It is not covered by tests currently only because the skele UI
is disabled by default.

Depends on D90467

Differential Revision: https://phabricator.services.mozilla.com/D90607

widget/nsIWidget.h

@@ -1857,6 +1857,15 @@ class nsIWidget : public nsISupports {
    */
   virtual void EnableIMEForPlugin(bool aEnable) {}
 
+  /**
+   * MaybeDispatchInitialFocusEvent will dispatch a focus event after creation
+   * of the widget, in the event that we were not able to observe and respond to
+   * the initial focus event. This is necessary for the early skeleton UI
+   * window, which is displayed and receives its initial focus event before we
+   * can actually respond to it.
+   */
+  virtual void MaybeDispatchInitialFocusEvent() {}
+
   /*
    * Notifies the input context changes.
    */

widget/windows/nsWindow.cpp

@@ -601,6 +601,7 @@ nsWindow::nsWindow(bool aIsChildWindow)
   mMouseInDraggableArea = false;
   mDestroyCalled = false;
   mIsEarlyBlankWindow = false;
+  mWasPreXulSkeletonUI = false;
   mResizable = false;
   mHasTaskbarIconBeenCreated = false;
   mMouseTransparent = false;
@@ -894,6 +895,7 @@ nsresult nsWindow::Create(nsIWidget* aParent, nsNativeWidget aNativeParent,
   if (aInitData->mWindowType == eWindowType_toplevel && !aParent) {
     mWnd = ConsumeEarlyBlankWindowHandle();
     if (mWnd) {
+      mWasPreXulSkeletonUI = true;
       ::SetWindowLongPtrW(mWnd, GWL_STYLE, style);
       ::SetWindowLongPtrW(mWnd, GWL_EXSTYLE, extendedStyle);
     }
@@ -8674,6 +8676,12 @@ bool nsWindow::SynchronouslyRepaintOnResize() {
   return !gfxWindowsPlatform::GetPlatform()->DwmCompositionEnabled();
 }
 
+void nsWindow::MaybeDispatchInitialFocusEvent() {
+  if (mWasPreXulSkeletonUI && ::GetActiveWindow() == mWnd) {
+    DispatchFocusToTopLevelWindow(true);
+  }
+}
+
 already_AddRefed<nsIWidget> nsIWidget::CreateTopLevelWindow() {
   nsCOMPtr<nsIWidget> window = new nsWindow();
   return window.forget();

widget/windows/nsWindow.h

@@ -370,6 +370,7 @@ class nsWindow final : public nsWindowBase {
       mozilla::widget::CompositorWidgetInitData* aInitData) override;
   bool IsTouchWindow() const { return mTouchWindow; }
   bool SynchronouslyRepaintOnResize() override;
+  virtual void MaybeDispatchInitialFocusEvent() override;
 
  protected:
   virtual ~nsWindow();
@@ -605,6 +606,7 @@ class nsWindow final : public nsWindowBase {
   bool mOpeningAnimationSuppressed;
   bool mAlwaysOnTop;
   bool mIsEarlyBlankWindow;
+  bool mWasPreXulSkeletonUI;
   bool mResizable;
   DWORD_PTR mOldStyle;
   DWORD_PTR mOldExStyle;

xpfe/appshell/AppWindow.cpp

@@ -257,6 +257,8 @@ nsresult AppWindow::Initialize(nsIAppWindow* aParent, nsIAppWindow* aOpener,
   // Attach a WebProgress listener.during initialization...
   mDocShell->AddProgressListener(this, nsIWebProgress::NOTIFY_STATE_NETWORK);
 
+  mWindow->MaybeDispatchInitialFocusEvent();
+
   return rv;
 }