Backed out changeset 1f44d19bb3a9 (bug 1891063) for causing bc failures on browser_test_autoscrolling_in_extension_popup_window.js CLOSED TREE

widget/windows/nsWindow.cpp

@@ -8299,10 +8299,35 @@ void nsWindow::PickerClosed() {
 }
 
 bool nsWindow::WidgetTypeSupportsAcceleration() {
-  if (IsPopup() && DeviceManagerDx::Get()->IsWARP()) {
-    return false;
-  }
-  return true;
+  // We don't currently support using an accelerated layer manager with
+  // transparent windows so don't even try. I'm also not sure if we even
+  // want to support this case. See bug 593471.
+  //
+  // Windows' support for transparent accelerated surfaces isn't great.
+  // Some possible approaches:
+  //  - Readback the data and update it using
+  //  UpdateLayeredWindow/UpdateLayeredWindowIndirect
+  //    This is what WPF does. See
+  //    CD3DDeviceLevel1::PresentWithGDI/CD3DSwapChainWithSwDC in WpfGfx. The
+  //    rationale for not using IDirect3DSurface9::GetDC is explained here:
+  //    https://web.archive.org/web/20160521191104/https://blogs.msdn.microsoft.com/dwayneneed/2008/09/08/transparent-windows-in-wpf/
+  //  - Use D3D11_RESOURCE_MISC_GDI_COMPATIBLE, IDXGISurface1::GetDC(),
+  //    and UpdateLayeredWindowIndirect.
+  //    This is suggested here:
+  //    https://docs.microsoft.com/en-us/archive/msdn-magazine/2009/december/windows-with-c-layered-windows-with-direct2d
+  //    but might have the same problem that IDirect3DSurface9::GetDC has.
+  //  - Creating the window with the WS_EX_NOREDIRECTIONBITMAP flag and use
+  //  DirectComposition.
+  //    Not supported on Win7.
+  //  - Using DwmExtendFrameIntoClientArea with negative margins and something
+  //  to turn off the glass effect.
+  //    This doesn't work when the DWM is not running (Win7)
+  //
+  // Also see bug 1150376, D3D11 composition can cause issues on some devices
+  // on Windows 7 where presentation fails randomly for windows with drop
+  // shadows.
+  return mTransparencyMode != TransparencyMode::Transparent &&
+         !(IsPopup() && DeviceManagerDx::Get()->IsWARP());
 }
 
 bool nsWindow::DispatchTouchEventFromWMPointer(