walk issue reproduction

I put together this repo to demonstrate two issues that I've encountered with tailscale/walk. The parent fork does not demonstrate these issues.

• The tab key cannot be used to move between elements in a main window
• There is an "overlay" bar at the top of the MainWindow. This happens most of the examples (which use MainWindow) that I've tested.

Demonstration

The video below was run (go run .) on Windows Server 2022 using Go 1.24.1 via RDP.

repro-win2022.mp4

The video below was run (GOOS=windows go build -o test.exe . && wine64 test.exe) locally on Linux.

repro-linux-wine.mp4