How to reproduce:
1. Open the “Delete.zip“ Project
2. Open the “SampleScene“
3. Open the PolyBrush Window (Tools > PolyBrush > PolyBrush Window)
4. Select the last mode (“Texture“ mode)
5. Select the 4 Plane GameObjects in the Scene view or the Hierarchy
6. Select the “Brush Tool“
7. Paint any of the provided textures on the Planes
8. Drag the Mouse over and out of the bounds of the 4 Plane GameObjects in the Scene view
8. Observe the Texture List in PolyBrush Window

Expected result: The list does not disappear
Actual result: The list disappears

Reproducible in: 1.1.8 (2021.3.44f1, 2022.3.49f1, 6000.0.20f1)
Not reproducible in: 1.1.6 (2021.3.44f1, 2022.3.49f1, 6000.0.20f1)

Reproduced on: Windows 11 Pro (23H2)
Not reproduced on: No other environment tested

Note: If the Mouse is dragged fast enough for the Scene view to not update the brush gizmo, the list will remain visible