Unused Separation line is used in the Context Menu of the Sprite Library Editor Window

Steps to reproduce:

1. Open any Project with the 2D Animation Package installed
2. Navigate to Window > 2D > Sprite Library Editor
3. Create a Sprite Library Asset as prompted
4. Create a Category
5. Right click in the Labels section of the Window
6. Right click a second time and observe the bottom of the context menu

Actual results: An unused separation line is used at the bottom of the Context Menu

Expected results: No unused separation line is used at the bottom of the Context Menu

Reproducible with versions: 10.2.2 (6000.0.62f1), 12.0.3 (6000.2.13f1), 13.0.2 (6000.3.0f1), 14.0.2 (6000.5.0a1)

Tested on (OS): Windows 11