Unused separation line appears when selecting the "Runtime" dropdown in Project Preview Theme Project Settings the second time

Unity: UI Toolkit Authoring Framework

6.6.X

6.5.X

6.4.X

Minor cosmetic issue that no longer reproduces on trunk as we have multiple themes (runtime + debug theme)

Steps to reproduce:

Open any Project
Navigate to Edit > Project Settings > UI Toolkit
In the "Project Preview Theme" section open the dropdown menu for "Runtime" and observe the dropdown options
Close and open the Dropdown Menu a second time

Actual results: When opening the Dropdown Menu a second time an unused separation line appears

Expected results: No separation line is used when there are no options to separate in a dropdown menu

Reproducible with versions: 6000.4.0a5, 6000.5.0a2

Not reproducible with versions: 6000.0.63f1, 6000.2.14f1, 6000.3.0f1 (No Project Settings for Project Preview Theme)

Tested on (OS): Windows 11