Strange white bar when maximizing files window on certain monitor(s)

[JohRest]

Describe the bug

I've discovered that on my Dell E2011H (1600x900 native) monitor when in dark mode I do see a slim white bar at the top of the window when I maximize the window on that monitor. I do think it is the window border, which in windows is colored differently than the rest of the title bar. To make it even harder I do not see the same behavior on my main monitor:

I think it's a minor thing, so yes, the priority of that is exceptionally low. I've experienced this in the file app (https://github.com/files-community/Files) which is according to their devs using winUI. So I'm trying to address here with you, if possible.

Steps to reproduce the bug

switch to dark mode
bring files to specific monitor
expand it to fill the whole screen
a small white area appears on the very top

Expected behavior

the expected behavior would be that the white area would be colored the same way as the rest of the title bar when the application windows goes full screen.

Screenshots

NuGet package version

None

Windows version

Windows 11 (22H2): Build 22621

Additional context

The issue in the files repo can be found here:

files-community/Files#13763

[kmgallahan]

Check if you have something like Dell Display Manager running in the background, kill it, and then see how things behave.

[ranjeshj]

@JohRest is this just for the files app? I cannot seem to repro this with any of the other apps that are on winui3 or winui2.

[yaira2]

@ranjeshj seems to be the same as #8947.

[Diegorro98]

It happens also to me, but only in monitors with 100% escale. I have two monitors, one with 2560 x 1440 resolution and 125% scale, and other with 1440 x 1080 resolution with 100%. It only happens in the second one, and if I change the scale of the first one to 100% it also happens there.

I've just installed Windows App SDK v1.4.3, which solved #8947, but this issue is still happening in the same way.

[jarno9981]

It happens also to me, but only in monitors with 100% escale. I have two monitors, one with 2560 x 1440 resolution and 125% scale, and other with 1440 x 1080 resolution with 100%. It only happens in the second one, and if I change the scale of the first one to 100% it also happens there.

I've just installed Windows App SDK v1.4.3, which solved #8947, but this issue is still happening in the same way.

Habbens on my winui3 app to when maximizing on bigger screens

[LucaCris]

I fully confirm... white line on some monitors only...

(try to save image out of browser white page)

Introduced in 1.4...

[Diegorro98]

I can confirm that the issue still happens in some monitors at 100% scale (changing the scale fixes the issue).
With my office monitor some time ago I was having this issue also, but I just realized that it is not happening anymore (maybe because #8947), and at my house monitors, in my main monitor (the one with 1440p resolution) the issue was also fixed, but with my secondary (the one with 1080p resolution) the issue happens with two different computers (work laptop and personal PC).

In order to provide more information to help finding the issue:

• both computers have NVIDIA GPUs
• monitor is from AOC, specifically AOC G2460VQ6.

[stevenbrix]

@ranjeshj what's the status here? this is pretty easy to run into given the wide array of different resolution devices ppl use on windows

[LucaCris]

Same WinUI3 App run twice on my monitors... Left (2K 27") is OK, right (FHD 24") has the top white line.

Thanks...