Are you referring to the navigation for the Dashboard? If so, that’s actually a change with WordPress, not Mystique.
With the release of WordPress 3.3 they’re no longer using the drop-down arrows. Instead, they’re utilizing hover menus that display the same info as the drop-downs did, so now instead of having to click on the drop-down to access the sub-menus, all you have to do is hover your mouse over it.
Here’s a link with info on all of the major changes with 3.3:
https://www.ads-software.com/news/2011/12/sonny/
If you are indeed talking about a theme functionality issue (i.e. a front-end issue) post a link to your site so we can see exactly what’s going on.