Up/Down buttons of the DomainUpDown/NumericUpDown control scale incorrectly at different DPI

[LeafShi1]

.NET version

11.0.0-preview.7.26365.101

Did it work in .NET Framework?

Yes

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No

Issue description

When launching the application on a primary monitor set to 175% scaling and then changing the System Scale parameter to 100%, the "Up" and "Down" buttons—which were expected to scale down—actually became larger.
Conversely, when changing the scaling to 250%, the "Up" and "Down" buttons—which were expected to scale up—actually became smaller.

• The same issue occurs when moving the application between screens with different DPI settings.
• Everything works correctly in Classic mode.
• The display returns to normal after restarting the app.

Recording.2026-07-20.021407.mp4

Steps to reproduce

1. Create a WinForms application targeting .NET 11
2. Set VisualStylesMode = VisualStylesMode.Net11
3. Add a DomainUpDown
4. Run the app in main screen(150%)
5. Change the system -> Display-> Scale to 100%
6. Change the system -> Display-> Scale to 250%

[KlausLoeffelmann]

Good catch!

[SimonZhao888]

This issue will fix at PR: #14887