"Add a graph node" menu cannot be resized to a smaller window on Ubuntu

Steps to reproduce:

1. Create and open a new project
2. Set up Graph Toolkit example from the documentation
3. Create a graph and open it
4. Press the Space key to open "Add a graph node" menu
5. Resize it

Actual results: The window cannot be resized down

Expected results: The window can be resized down

Reproducible with versions: 0.4.0-exp.1 (6000.3.0a6), 6000.4.5f1, 6000.5.0b6, 6000.6.0a4

Can’t test with versions: 6000.0.74f1, 6000.3.14f1 (Graph Toolkit unavailable)

Reproduced on (OS): Ubuntu 24.04
Not reproduced on (OS): Windows 11 Pro (25H2)