Invisible item at the top of the Variables selection dialog is present and can be selected when navigating the Dialog using arrow keys

Steps to reproduce:

1. Open any Project
2. Create a UIDocument Asset in the Project Browser and open it in UI Builder
3. In the Inspector add a Visual Element and select it
4. Next to a Property with internal variables available (e.g. Opacity, Color) click the kebab menu on the left side and select "Set variable"
5. Use arrow keys to navigate the list to go the the very bottom and the very top

Actual results: An invisible item is at the top of the list that can be selected with arrow keys while nothing is visually selected

Expected results: A UX oversight is present here, either the top item should be highlighted when the dialog is first opened and users shouldn't be able to navigate to a visually not present item in the list or the first time the arrow down key is pressed and the first item is then visually selected users shouldn't be able to go back to the invisible item

Reproducible with versions: 6000.3.14f1, 6000.4.4f1, 6000.5.0b5, 6000.6.0a4

Can’t test with versions: 6000.0.73f1 (No Variables in selector)

Tested on (OS): Windows 11