Set fixed / max width for a workspace control?

Feel like I’m losing my mind trying to do this, it seems “widthProperty” doesnt really do anything on workspaceControl?

I’ve got this control, either floating or docked, I wanna limit it’s width to 200, or fix it at 200, and I can’t for the life of me figure out how. When it’s docked and you do anything to mayas layout sometimes it’ll just expand itself and be like, 600 wide and myself and my users are constantly having to resize it.

https://imgur.com/YODdHYz