This is a test program for creating a new window in Avalonia UI.

Steps for creating the code:

1. Create an MVVW application with "dotnet new avalonia.mvvm -o MyApp"
2. Duplicate the code of the MainWindow to create a SubWindow
3. Make the SubWindow open when the button in the MainWindow is pressed

Test environment:

1. Windows 11 .NET 8 (Avalonia ui Version 11.0.1)
2. Raspberry Pi Zero 2 W + Raspbian (Avalonia ui Version 11.0.1)

Problems confirmed on Raspberry Pi

When opening a SubWindow, the background of the SubWindow temporarily becomes all black, and then the contents of the SubWindow are displayed. I want to fix this, but I don't know how. (The same phenomenon probably occurs on Windows 11. I think that Windows 11 is fast enough that it is not noticeable.)

Only MainWindow

SubWindow appeares, but contents are filled with black

SubWindow appears perfectly