Steps to reproduce:
1. Create new Unity project using empty URP 3D Template
2. Install OpenXR Plugin via Package Manager
3. Once installed, to to Project Settings > XR Plug-in Management
4. Select “Unity Mock HMD” in Plug-in Providers
5. Wait for package to install
6. Open Render Texture Viewer window (Window > XR > Mock HMD > Render Texture Viewer)
7. Enter Play Mode
8. Exit Play Mode
9. Observe the Console window
Actual results: “GUI Error: Invalid GUILayout state in view. Verify that all layout Begin/End calls match
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)” error is thrown in the Console window
Expected results: No errors are thrown in the Console window
Reproducible with versions: 1.15.1 (6000.0.61f1, 6000.2.10f1), 1.16.0 (6000.3.0b8, 6000.4.0a3)
Tested on (OS): Windows 11, macOS Silicon Tahoe 26.0 (M1)