Duplication errors occur when multiple style sheets are loaded and applied to a document in UI Builder

1. Install Unity 2023.3.0b3 for scenario week
2. Install UI Toolkit and use UI Builder to try and make a custom slider
3. Load multiple style sheets and apply them to a document in UI Builder
4. Right click an existing selector and duplicate it
5. Note functionality:

Bug:  When multiple style sheets are loaded and applied to a document in UI Builder, if the user right clicks an existing selector and duplicates it, it always gets duplicated into the first USS regardless of which USS the selector was in when it was duplicated.

 

Note: we only had one report of this in the channel - not sure how prevalent it is https://unity.slack.com/archives/C06CT8REG6T/p1705292366229479?thread_ts=1705264628.158019&cid=C06CT8REG6T