Visual bug when opening windows on home PC driving me crazy.

AgathePower said:

Hi @CarameloGay, hi all,

I'm really glad I found your post.

I'm having the exact same problem. The window border appears in a wrong position for a fraction of a second just before the window is displayed.

The problem started about 4 or 5 months ago (end of 2025). It exist on Windows 11 25H2 (not yet tested 25H1), on 2 computers, and on dozens of VMs that I reinstall every day for work (I'm a developer).

It also appear on Windows 11 ARM installed on VMware Fusion on Macbook Pro M4. This excludes NVIDIA card or driver issue.

To test yourself as explained by @CarameloGay: click on Windows taskbar, hold the Alt key down, and press F4 repeatedly. Each time you press F4, the Shut Down dialog box opens and closes. Repeat the operation so that the window appears and then closes, and while you are doing this, stare at the upper left corner of the screen: you will sometimes see a black rectangular outline flashing.

This glitch occurs regularly with all Windows 11 dialog boxes randomly.

Click to expand...

Damn right, still happening to this day.

Fortunately, I found a workaround, need to use a third party app though - DWMGLASSBLUR (avast marked this as suspicious but it's a well known app, safe).

Just download from here:


Extract to C:\DWMBlurGlass

Run it, go to Symbols and download that.

Then just use the attached config file (change extension to ini), I made it to only correct window borders colors to the correct windows light theme colors, rest of settings I kept the same exact appearance of stock Windows 11. You can customize those if you like but I see no need personally.

When windows updates, it'll throw an error at boot, just download Symbols again.

Windhawk has a mod that also fixes this issue (Windows 11 Custom Title Bar Colours) but there's a bug with it, explorer tabs have their colors messed up.

CarameloGay said:

Screen recording software (e.g. OBS) does not capture the issue

Click to expand...

Yes it does.

Watch 2026-03-06 22-58-30 | Streamable

AgathePower said:

Yes it does.

Watch 2026-03-06 22-58-30 | Streamable

Click to expand...

Indeed it does, mistake on my part :) I got it showing in obs and stock screen capture.

CarameloGay said:

Damn right, still happening to this day.

Fortunately, I found a workaround, need to use a third party app though - DWMGLASSBLUR (avast marked this as suspicious but it's a well known app, safe).

Just download from here:

Release 2.3.1 Release · Maplespe/DWMBlurGlass

增加了一个选项 "关闭Dcomp帧率限制" 在"高级"页面, 允许你解除背景的30帧刷新率限制 #460 增加了一个内置优化, 标题栏字幕按钮的颜色现在会根据你设置的混合颜色自动切换亮暗样式 #279 #380 #427 崩溃信息弹窗增加了一个"重试"按钮, 如果dwm崩溃, 可以点击"重试"尝试重新加载DWMBlurGlass 稳定性改善和优化 GUI样式优化 缩减了生成dump文件时的体...

github.com

Extract to C:\DWMBlurGlass

Run it, go to Symbols and download that.

Then just use the attached config file (change extension to ini), I made it to only correct window borders colors to the correct windows light theme colors, rest of settings I kept the same exact appearance of stock Windows 11. You can customize those if you like but I see no need personally.

When windows updates, it'll throw an error at boot, just download Symbols again.

Windhawk has a mod that also fixes this issue (Windows 11 Custom Title Bar Colours) but there's a bug with it, explorer tabs have their colors messed up.

Click to expand...

I just tested and it effectively suppress the glitch! Thank you

Out of curiosity, we could test every version of Windows 11 since September 2025 to see which one created the bug...

I’m not quite able to see your problem, but resently I had a annoing problem with some flashing edges in Windows 25H2 when opening windows. There is a setting, that ad a small border on popup windows, and it was the course. Don’t know how it got activated, but it not working propper, because of the very annoying short flash on edges before it settles right.

Jorgen E said:

I’m not quite able to see your problem, but resently I had a annoing problem with some flashing edges in Windows 25H2 when opening windows. There is a setting, that ad a small border on popup windows, and it was the course. Don’t know how it got activated, but it not working propper, because of the very annoying short flash on edges before it settles right.

Click to expand...

Nope. I appreciate your answer but this runs much deeper than a simple windows appearance setting.
This is a dwm.exe issue. So far, the only way to get around it is to hook on to dwm.exe and either use DWMGlassBlur (100% working) or using a windhawk mod (Windows 11 Custom Title Bar Colours - Has bugs)

Jorgen E said:

I’m not quite able to see your problem, but resently I had a annoing problem with some flashing edges in Windows 25H2 when opening windows. There is a setting, that ad a small border on popup windows, and it was the course. Don’t know how it got activated, but it not working propper, because of the very annoying short flash on edges before it settles right.

Click to expand...

Here is the glitch, frame by frame. The 2nd picture (border1.webp) is the misplaced outline. The 4th picture (border3.webp) is when the window fade-in start.

Looks like DWM is preparing to draw the window but has not any position data yet and attempts to draw it top left of the screen. Then it gets the correct upper left corner coordinates and immediately deletes it from top left and draws it on the correct position. This happens too fast it looks like flashing. I haven't tested it on my computer, but I will and report back. If it doesn't show, it means my nVidia Geforce RTX 3050 is too fast that DWM doesn't has the time to draw the window top left first.

PS: I confirmed, it doesn't happen on my main PC (see 2nd system specs).

spapakons said:

Looks like DWM is preparing to draw the window but has not any position data yet and attempts to draw it top left of the screen. Then it gets the correct upper left corner coordinates and immediately deletes it from top left and draws it on the correct position. This happens too fast it looks like flashing. I haven't tested it on my computer, but I will and report back. If it doesn't show, it means my nVidia Geforce RTX 3050 is too fast that DWM doesn't has the time to draw the window top left first.

Click to expand...

RTX 3050 is the exact graphics card I'm running, believe me, it's noticeable.

This also appens during Windows setup.

Here is Windows 11 25H2 February update. I pressed Shift+F10 to bring up command prompt, opened Notepad, then typed Ctrl+O and Cancel. Glitch first occurs around 00:28.

Are you sure all your drivers are updated? I would make sure I update the chipset drivers first, if available, and then install the official graphics drivers directly from Intel/nVidia/AMD. Don't trust Windows Update. About a month ago I realized some glitches when playing some videos and upon checking MPC-HC was using a software decoder (no hardware acceleration) when the decoder in LAV Video filter was set to DXVA2. I had to set it to the older CUVID to force using nVidia CUDA because my card wasn't detected properly for some reason. I checked some settings and then I decided to load nVidia Control Panel to check my video settings. But when I right-clicked on the desktop I discovered that nVidia Control Panel wasn't available and this got me suspicious. Sure enough, Windows Update had replaced my official Jan 2026 nVidia driver with an older Dec 2025 version without the nVidia Control Panel. Once I downloaded the official nVidia Jan 2026 driver directly form nVidia and reinstalled the issue was gone. I didn't have to change any settings in nVidia Control Panel. So you too, make sure you install the latest OFFICIAL graphics drivers and then check if the issue persists.

TIP: For those with old graphics cards and no newer official driver is available, install the latest official driver and to prevent Windows Update replacing it, you must hide (block) the respective update using a tool such as Microsoft's Windows Update Show/Hide Tool or Windows Automatic Updates Manager (WAU Manager). Both are available in Major Geeks:

With the exact same VM:

We can conclude that glitch is present on 25H2 Sept 2025, 24H2 Oct 2025, but is not present on 23H2 Oct 2025.

spapakons said:

Are you sure all your drivers are updated?

Click to expand...

I think this is not related to driver update as the problem also occurs on Windows 11 ARM on VMware Fusion on Macbook Pro M4.

Have you tried to disable visual effects (transparency, animations, fades) and check again?

spapakons said:

Have you tried to disable visual effects (transparency, animations, fades) and check again?

Click to expand...

I tried this:

Windows 11 24H2 RTM (Insider Preview 26100.1, released April 2024) also has the issue.

Okay, I found the problem.

The issue appears in Windows 11 24H2 build 25179 (8/10/2022) and is present in all 24H2 and 25H2 builds. It is absent in Windows 11 24H2 build 25174 (8/3/2022) and all previous builds (including 23H2 and 22H2). In any case, it never existed before.

The release notes for build 25179 includes the following:

[Windowing]​

• Fixed an issue where when resizing certain app windows near the edge of the screen when using mixed DPI monitors might unexpectedly cause the window to jump and shrink.

This probably be what caused this bug.


Build 25174 (there is no bug):

Build 25179 (window outline sometime appears just before the winver dialog):

List of builds:

These look like Insider's builds. I haven't seen this bug on standard builds, such as 26200.xxxx for 25H2.

spapakons said:

These look like Insider's builds. I haven't seen this bug on standard builds, such as 26200.xxxx for 25H2.

Click to expand...

Here is a frame by frame from my previous capture on post #35 with 25H2 retail build.

Do you see rectangular outline?

Now that I saw your photos, I have seen it too, but occasionally. It doesn't happen too often and I cannot reproduce it. This is usually when some startup application opens briefly and then closes or minimizes before the whole window of the application appears. Like I said it doesn't happen too often and I cannot reproduce it.