I don't think that group collapse/expand via ui_control is supported at the moment. At least I couldn't find any reference in the docs. A quick look at the code didn't reveal anything either.
As it is a funky Thursday I have added the ability to open and close groups that can be opened and closed by the user, to the ui_control command. Now in master branch - (not yet on npm).
Syntax is similar to that for hide and show messages - but is open and close of course...