WPF apps don't play nicely with the auto-hide taskbar setting

Copied from internal OS bug #35513385. Requires Windows 10.

Repro steps:
1) Right-click on your Windows 10 taskbar, go to Taskbar Settings and turn on "Automatically hide the taskbar in desktop mode".
2) In VS, create a new WPF app (for example, File->New->Project (WPF App (.NET Framework) (C#)) in VS).
3) Launch your new app and maximize it.
4) Run your cursor to the side of the screen where the taskbar is hidden.

Expected result: the taskbar becomes visible (like it does if you maximize other apps, e.g. Microsoft Edge)
Actual result: the taskbar remains hidden.

This repros with .NET 6.0 preview 7, and .NET framework 4.5