Describe the bug
Drag Window to another position sometimes bad

To Reproduce
Steps to reproduce the behavior:

1. Run the example 'custom_window_frame'
2. Drag the window bar to another position
3. Repeat step 2 multiple times
4. Seeing the error that the window cannot be dragged

Screenshots
https://github.com/emilk/egui/assets/108512675/d9c72117-4082-4f4a-b0c3-251b7db0d88c

Desktop (please complete the following information):

• OS: Windows 11
• Version 25.