.NET version

10.0.100-rc.2.25466.103

Did it work in .NET Framework?

Not tested/verified

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

DarkMode is a new feature in .NET 10

Issue description

In Windows Forms, when a Button control has its FlatStyle set to FlatStyle.Popup, it does not show any visual feedback (such as border change) when the mouse hovers over it under Dark Mode. This breaks expected UI behavior and provides no indication of interactivity.

Dark mode: has a problem

Classic mode: work well

Steps to reproduce

1. Create a new Windows Forms application
2. Add a Button control to the form
3. Set button1.FlatStyle = FlatStyle.Popup
4. Set app under Dark mode in program.cs file:
   Application.SetColorMode(SystemColorMode.Dark);
5. Run the application
6. Hover the mouse over the button to observe