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I disabled shadows in SystemPropertiesPerformance.exe show shadows under windows and set Title bars and windows borders in "Colors" settings and noticed the Task Manager window is missing right & bottom black line edge (on the image the line breaks near the "X" button, not going down continiuosly):

enter image description here

Sometimes it appears if I resize the window but then disappear.

On a 4K external display without scaling sometimes lines are shown not as black but as blue: as if graphic engine (DirectX 9??) decided that thickness of line is less than 1px so rendered it with subpixels.

I suspect that this is due to new Windows 10 hi-DPI https://en.wikipedia.org/wiki/Desktop_Window_Manager in combination with low end integrated Intel GPU.

Any ideas?

UPDATE This another laptop I've seen lots of strange artifacts on display, like some blue lines are displayed as black, crazy rainbow blurring for fonts, etc even when I disabled ClearType or Grayscale.

Filling the screen with monotonous patterns resulted in different square patterns.

Magnification of screenshots showed no problems. This gave me an idea that I have additional problems with hardware.

Finally, I was able to "fix" displaying by selecting different refresh frequency (59.940Hz caused the problem, 59.997Hz works amazingly sharp and precise):

Frequency selection

gavenkoa
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  • The question why borders of the app are missing and sometimes re-appear. Is it driver or low end GPU issue or driver problems... – gavenkoa Jan 15 '23 at 11:08
  • Did you perhaps switch DPI scaling without logging out and logging in before this issue occurs? – Daniel B Jan 15 '23 at 11:48
  • @DanielB You are right! I attached external 4K display and reset 150% to 100% (but only for that display). Restart of the laptop fixed the problem but I haven't tried to attach external display yet. – gavenkoa Jan 15 '23 at 13:15

2 Answers2

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Windows (10) Task Manager is only “system” DPI aware. That means it cannot properly deal with DPI scaling changes during a session. It will render at the scaling level the session started at and Windows will zoom/shrink the rendered output to the required size. When shrinking, this can result in fine lines disappearing because the scaling algorithm Windows uses isn’t that great. That’s also why the CPU name label is blurry in your screenshot.

Modern applications are per-monitor DPI aware (v1 or, better, v2). They can not only respond to DPI changes in general but can also achieve the best possible quality on setups with multiple monitors with different scaling levels.

You can check a process’ DPI awareness using Task Manager. In the “Details” tab, enable the “DPI Awareness” column.

For applications that are only “system” DPI aware, it may be necessary to log out and log back in again for changes to take effect. A reboot is not required.

You can read about the technical details of High DPI Desktop Application Development on Microsoft Learn (formerly MSDN). The GPU or its drivers are unrelated.

Daniel B
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  • Great comment! I've just bought 4k display and thought problems in hardware / drivers but I've heard that scaling is still problematic on Windows 10... – gavenkoa Jan 15 '23 at 15:15
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There is no way to answer that question, except empirically. Only trying another driver, or another graphic card, may possibly answer it.

Most likely this is bad programming by the developer of the application, that hasn't programmed it in a DPI-aware manner. It's not the first case I have seen of Windows dialogs that misbehave under a certain resolutions that weren't foreseen by the developer.

harrymc
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