[Bug 54888] New: Transparent window are displayed as black background window on wine

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=54888

Bug ID: 54888
           Summary: Transparent window are displayed as black background
                    window on wine
           Product: Wine
           Version: 8.6
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: -unknown
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

Some transparent windows are displayed as black background window. Here is a
simple WPF window program that can reproduce this issue. On Windows, all parts
are transparent except for the graphics and text in the middle, but it has a
black background on Wine. It achieves transparency only by adding the following
code to the window constructor (the main point is that WindowChrome is used
instead of AllowTransparent):
WindowStyle = WindowStyle.None;
ResizeMode = ResizeMode.NoResize;
Background = Brushes.Transparent;
WindowChrome.SetWindowChrome(this, new WindowChrome { GlassFrameThickness = new
Thickness(-1) });

Download link of the demo program:
https://drive.google.com/file/d/1MCrnb1N6cLUzVoX_vO4tFO4qlS_qhAwi/view?usp=s...

Other clues: Transparent windows implemented using AllowTransparent are valid
on Wine, while those implemented using WindowChrome are invalid. On Windows,
transparent forms implemented using WindowChrome are frequently used due to
better performance(usually). According to my pre investigation,
AllowTransparent seems to be implemented using GDI, but WindowChrome mainly
uses the DWM API

System architecture:
x86_64
Ubuntu 20.04
wine 8.6
wine-mono 7.4.0