Bug 1772404 - Corner snapping for Windows and Linux. r=mhowell,mconley

Differential Revision: https://phabricator.services.mozilla.com/D151162

toolkit/components/pictureinpicture/content/player.js

@@ -989,7 +989,11 @@ let Player = {
     let quadrant = this.determineCurrentQuadrant();
     let dragAction = this.determineDirectionDragged();
 
-    if (event.metaKey && AppConstants.platform == "macosx" && dragAction) {
+    if (
+      ((event.ctrlKey && AppConstants.platform !== "macosx") ||
+        (event.metaKey && AppConstants.platform === "macosx")) &&
+      dragAction
+    ) {
       // Moving logic based on current quadrant and direction of drag.
       switch (quadrant) {
         case TOP_RIGHT_QUADRANT:

widget/windows/nsWindow.cpp

@@ -5652,6 +5652,20 @@ bool nsWindow::ProcessMessageInternal(UINT msg, WPARAM& wParam, LPARAM& lParam,
         NotifySizeMoveDone();
       }
 
+      // Windows spins a separate hidden event loop when moving a window so we
+      // don't hear mouse events during this time and WM_EXITSIZEMOVE is fired
+      // when the hidden event loop exits. We set mDraggingWindowWithMouse to
+      // true in WM_NCLBUTTONDOWN when we started moving the window with the
+      // mouse so we know that if mDraggingWindowWithMouse is true, we can send
+      // a mouse up event.
+      if (mDraggingWindowWithMouse) {
+        mDraggingWindowWithMouse = false;
+        result = DispatchMouseEvent(
+            eMouseUp, wParam, lParam, false, MouseButton::ePrimary,
+            MOUSE_INPUT_SOURCE(),
+            mPointerEvents.GetCachedPointerInfo(msg, wParam));
+      }
+
       break;
     }
 
@@ -5679,6 +5693,7 @@ bool nsWindow::ProcessMessageInternal(UINT msg, WPARAM& wParam, LPARAM& lParam,
       if (ClientMarginHitTestPoint(GET_X_LPARAM(lParam),
                                    GET_Y_LPARAM(lParam)) == HTCAPTION) {
         DispatchCustomEvent(u"draggableregionleftmousedown"_ns);
+        mDraggingWindowWithMouse = true;
       }
 
       if (IsWindowButton(wParam) && mCustomNonClient) {

widget/windows/nsWindow.h

@@ -756,6 +756,7 @@ class nsWindow final : public nsBaseWidget {
   bool mResizable = false;
   bool mForMenupopupFrame = false;
   bool mIsPerformingDwmFlushHack = false;
+  bool mDraggingWindowWithMouse = false;
   DWORD_PTR mOldStyle = 0;
   DWORD_PTR mOldExStyle = 0;
   nsNativeDragTarget* mNativeDragTarget = nullptr;