Wayland: app freezes if viewport is behind main window

**Describe the bug**

When an immediate or deferred viewport is completely covered by the main window, the application stops responding until the viewport is brought to the front again.

https://github.com/user-attachments/assets/fb7a7293-b177-4c5b-9e7e-66cfae988c27

**To Reproduce**
Steps to reproduce the behavior:
1. Run the multiple_viewports example
2. Check either of the viewports
3. Move the child window on top of the main window
4. Click on the main window to bring it to the front
5. The app freezes

**Expected behavior**

The application should remain responsive.

**Screenshots**

**Desktop (please complete the following information):**
- OS: Fedora 40
- Browser N/A
- Version N/A

**Smartphone (please complete the following information):**
N/A

**Additional context**

OS: Fedora Linux 40 (Workstation Edition) x86_64
Host: Laptop (12th Gen Intel Core) A6
Kernel: 6.10.10-200.fc40.x86_64
Shell: bash 5.2.26
Resolution: 2256x1504
DE: GNOME 46.5
WM: Mutter
WM Theme: Adwaita
Theme: Adwaita-dark [GTK2/3]
Icons: Adwaita [GTK2/3]
CPU: 12th Gen Intel i7-1260P (16) @ 4.700GHz
GPU: Intel Alder Lake-P GT2 [Iris Xe Graphics]