fix minimise button being disabled when either a parent or a dialog.
fix minimise button being disabled when either a parent or a dialog.

AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia