Screen Reader Focus Not Maintained When Switching Windows

### Tested versions

- Reproducible in Godot 4.5 Beta 3

### System information

Godot v4.5.beta3 - Windows 11 (build 26100) - Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA RTX A1000 Laptop GPU (NVIDIA; 32.0.15.6641) - 12th Gen Intel(R) Core(TM) i7-12800H (20 threads) - 31.67 GiB memory. Using NVDA screen reader version 2025.1.2

### Issue description

Whenever one alt-tabs away from the editor window and comes back, the focus is reset back to what seems to be the top of the window, specifically on the "The Canvas item editor is not accessible at this time." "Grouping" (it shows as separate speech fragments). This is the case even if I tab over to any element in the window, e.g.,
- Tab over to Reset Zoom: 100.0 % button
- Alt-tab away, let another window take focus
- Alt-tab back to the editor
- Hear the "Canvas item not accessible" bit.

What should happen:
Focus should remain on the selected element, even if switching windows.

### Steps to reproduce

- Create a fresh Godot project
- Tab over to any element
- Alt-tab in and out of the window
- Witness the bug.

### Minimal reproduction project (MRP)

N/A