Menu bars rendered on full screen windows with with_transparency set are translucent

[npwoods]

Description

There seems to be a problem where if I have a window where:

1. The window was created with with_transparency(true);
2. The window has a menu bar
3. The window is full screen
   ...the menu bar seems to be translucent. Despite this, the menu bar is functional and upon pull down, the menus themselves are fine. This does not happen when the window is either not full screen, or not set with transparency.

Attached is a demonstration application that demonstrates this; just press X to toggle full screen.

I created the menus using raw Win32 APIs to eliminate the possibility that the muda crate could be doing something weird.

winit_transparency_bug_demo.zip

Windows version

Microsoft Windows [Version 10.0.19045.6093]

Winit version

0.30.11