On Raspberry Pi Zero 2 W, New window appears filled with black for a moment

[Az-kijitra]

I am trying to make an Avalonia UI application on Raspberry Pi Zero 2 W Raspbian.
In my environment, when I open a new window, the window once goes black, and then the content is displayed.

Step1. MainWindow open when starting the test application.

Step2. By pushing the button on the MainWindow. SubWindow is created but content area is filled with black

Step3. The contents of SubWindow is rendered

I have put the code I tested here AvaloniaOpenSubWindow.

I want to render the SubWindow contents without going Step2.
Any advice would be appreciated.

[seishinkouki]

try modify

Avalonia/src/Avalonia.X11/X11Window.cs

Line 109 in 68009f8

valueMask |= SetWindowValuemask.BackPixel | SetWindowValuemask.BorderPixel

-valueMask |= SetWindowValuemask.BackPixel | SetWindowValuemask.BorderPixel
-                         | SetWindowValuemask.BackPixmap | SetWindowValuemask.BackingStore
+valueMask |= SetWindowValuemask.BorderPixel
                         | SetWindowValuemask.BitGravity | SetWindowValuemask.WinGravity;

[Az-kijitra]

Sorry for the late reply. Thank you for your advice. Problem solved.