Combine with whatever aero commit worked this around in

not having this breaks aero in some circumstances

Author: K4sum1

widget/windows/nsWindow.cpp

@@ -2881,8 +2881,6 @@ bool nsWindow::UpdateNonClientMargins(bool aReflowWindow) {
     mNonClientOffset = NormalWindowNonClientOffset();
   }
 
-  UpdateOpaqueRegionInternal();
-
   if (aReflowWindow) {
     // Force a reflow of content based on the new client
     // dimensions.
@@ -7948,8 +7946,6 @@ void nsWindow::SetWindowTranslucencyInner(TransparencyMode aMode) {
   if (HasGlass()) memset(&mGlassMargins, 0, sizeof mGlassMargins);
   mTransparencyMode = aMode;
 
-  UpdateOpaqueRegionInternal();
-
   if (mCompositorWidgetDelegate) {
     mCompositorWidgetDelegate->UpdateTransparency(aMode);
   }
@@ -7971,40 +7967,6 @@ void nsWindow::SetWindowTranslucencyInner(TransparencyMode aMode) {
   }
 }
 
-void nsWindow::UpdateOpaqueRegion(const LayoutDeviceIntRegion& aRegion) {
-  if (aRegion == mOpaqueRegion) {
-    return;
-  }
-  mOpaqueRegion = aRegion;
-  UpdateOpaqueRegionInternal();
-}
-
-void nsWindow::UpdateOpaqueRegionInternal() {
-  MARGINS margins{0};
-  if (mTransparencyMode == TransparencyMode::Transparent) {
-    // If there is no opaque region, set margins to support a full sheet of
-    // glass. Comments in MSDN indicate all values must be set to -1 to get a
-    // full sheet of glass.
-    margins = {-1, -1, -1, -1};
-    if (!mOpaqueRegion.IsEmpty()) {
-      LayoutDeviceIntRect clientBounds = GetClientBounds();
-      // Find the largest rectangle and use that to calculate the inset.
-      LayoutDeviceIntRect largest = mOpaqueRegion.GetLargestRectangle();
-      margins.cxLeftWidth = largest.X();
-      margins.cxRightWidth = clientBounds.Width() - largest.XMost();
-      margins.cyBottomHeight = clientBounds.Height() - largest.YMost();
-      margins.cyTopHeight = largest.Y();
-
-      auto ncmargin = NonClientSizeMargin();
-      margins.cxLeftWidth += ncmargin.left;
-      margins.cyTopHeight += ncmargin.top;
-      margins.cxRightWidth += ncmargin.right;
-      margins.cyBottomHeight += ncmargin.bottom;
-    }
-  }
-  DwmExtendFrameIntoClientArea(mWnd, &margins);
-}
-
 /**************************************************************
  **************************************************************
  **

widget/windows/nsWindow.h

@@ -648,9 +648,6 @@ class nsWindow final : public nsBaseWidget {
   bool IsSimulatedClientArea(int32_t clientX, int32_t clientY);
   bool IsWindowButton(int32_t hitTestResult);
 
-  void UpdateOpaqueRegion(const LayoutDeviceIntRegion&) override;
-  void UpdateOpaqueRegionInternal();
-
   bool DispatchTouchEventFromWMPointer(UINT msg, LPARAM aLParam,
                                        const WinPointerInfo& aPointerInfo,
                                        mozilla::MouseButton aButton);
@@ -844,8 +841,6 @@ class nsWindow final : public nsBaseWidget {
 
   // Draggable titlebar region maintained by UpdateWindowDraggingRegion
   LayoutDeviceIntRegion mDraggableRegion;
-  // Opaque region maintained by UpdateOpaqueRegion
-  LayoutDeviceIntRegion mOpaqueRegion;
 
   // Graphics
   LayoutDeviceIntRect mLastPaintBounds;