WinUI 3 rounded main window

Question

How to make main window with rounded corners? I had a look on many videos and steps are quite simple.

• check SDK installed enter image description here
• create project c# Windows WinUI
• run app - after that a MainWindow appears with rounded corners.

But when project created by me the Mainwindow without rounded corners. enter image description here

Maybe I have to update windows up to 11?

Answer 1

Maybe I have to update windows up to 11?

Yes, correct.

Only on Windows 11 , the system automatically rounds top-level window corners for most apps as explained in the docs .

The APIs that apply rounded corners are not present in Windows 10 and earlier versions.