Apps with a custom background flash a white background for a couple frames on some devices

[1ctinus]

• .NET Core Version: (e.g. 3.0 Preview1, or daily build number, use dotnet --info) 6.0.100
• Windows version: (winver) Windows 11 10.0.22000
• Does the bug reproduce also in WPF for .NET Framework 4.8?:
• Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? If yes, please file the issue via the instructions here.
• Security issues and bugs should be reported privately, learn more via our responsible disclosure guidelines.

Problem description:
Apps with a custom background flash a white background for a couple frames on some devices (previously asked Stack overflow to no avail, pointed to likely a software issue)
Actual behavior:
Window flashes white before fully loading.
Expected behavior:
Window opens with the correct background color instantly
Minimal repro:

dotnet new wpf

edit MainWindow.xaml to have a background attribute

dotnet build

and run the app.

[singhashish-wpf]

@1ctinus Is this issue reproducible on previous windows versions/ previous version of .Net Core/ Framework also?

[1ctinus]

I compiled the program using msbuild 4.8 and running it on the latest version of dotnet, on a separate device running windows 10. the issue persisted.

[batzen]

This also started to happen on my machine like a week ago.
It's does not seem to be isolated to WPF as it also happens with Edge.
See (increased gif frame delay to 250 ms to make it really visible):

[1ctinus]

I am also having this exact same issue with win32 too.

[vishalmsft]

@1ctinus Can you please use Windows feedback channel to take this up. Hopefully, this issue can be closed.

[ZionGates]

I'm having the same issue, WPF on DOT NET CORE opens the window slower too, about 2 seconds slower.
However WPF on dot.net 4.8 sometimes didn't open at all periodically and just hung, at least they fixed that after 15 years...

[torum]

This is a very old known issue of WPF.

In fact, this has been annoyance since 2005!
https://social.msdn.microsoft.com/Forums/en-US/3960d6a6-e873-455c-9ddc-1e2dd32e090b/flickering-background-when-resizing-window?forum=wpf

The white background flash happens at start up and window resize (including maximizing). This is so obvious with a Window with fairly complex XAML layout with custom title bar using WindowChrome.

I can't believe this "bug" is still present in 2023.

[batzen]

@torum As i already wrote above, this is not a pure WPF issue. The underlying problem is caused by Windows itself.
ControlzEx has code to mitigate the white flash and the resize flickering.

[JanHadascok]

I would like to mention this workaround from SO.
Just set Window Opacity to 0 and then in Loaded event set it back to 1. Its dirty workaround but seems to be ok in my case.

[mhrastegari]

Any updates on this?

[lindexi]

@mhrastegari Could you describe your problem? As same as the author's ? And I think it is the Windows's issues not wpf