Project Preview Theme Runtime dropdown sets Default Runtime Theme file as default alphabetically instead of the newest created when creating multiple Default Runtime Theme files

Unity: UI Toolkit Controls

6.5.X

6.4.X

We're in a bit of a crunch for the beginning of this year so we're being very selective in what bugs we take on. We'll come back to this later.

Steps to reproduce:

Create a new Unity project using the Universal 3D template
Open the Project Settings window (Edit > Project Settings)
Open the UI Toolkit tab in the Project Settings window
Dock the Project Settings window somewhere so its visible at all times
Create a new Default Runtime Theme file with the name "ggg" (Assets > Create > UI Toolkit > Default Runtime Theme file)
Observe the Runtime dropdown under the Project Preview Theme
Repeat step 5 with the name "aaa"
Repeat step 6
Repeat step 5 with the name "zzz"
Repeat step 6

Actual results: The "zzz" theme is set as default in the Runtime dropdown

Expected results: The "aaa" theme is set as default in the Runtime dropdown

Reproducible with versions: 6000.4.0b3, 6000.5.0a4

Can’t test with versions: 6000.0.65f1, 6000.3.3f1 (due to no Project Preview Theme in the Project Settings)

Tested on (OS): MacOS Silicon Tahoe 26.1