FileDialog unable to be interacted with when launched from PopupWindow

### Tested versions

- Reproducible in 4.2.2 stable and 4.3 stable, untested in other versions

### System information

Godot v4.3.stable.mono - Windows 10.0.19045 - GLES3 (Compatibility) - Intel(R) UHD Graphics 620 (Intel Corporation; 25.20.100.6577) - Intel(R) Core(TM) i3-8130U CPU @ 2.20GHz (4 Threads)

### Issue description

When launched from a PopupWindow, either directly or via callback, the FileDialog window cannot be closed, moved, or meaningfully interacted with.

### Steps to reproduce

In the MRP, click the "save" button to directly launch the FileDialog window (this should work). Click the "save with popup" button to launch a PopupWindow which can launch the FileDialog. This FileDialog exhibits the strange behavior.

### Minimal reproduction project (MRP)

[FileDialogIssueMRP.zip](https://github.com/user-attachments/files/17078093/FileDialogIssueMRP.zip)