When you pop out the rightmost vent to paint it (2005-2007), there is a good chance that the bottom two clips that hold the trim to the dash are going to break off due to the cheaper plastics Ford started using. Because of this, when you pop your vent back in, it will be attached on the top, but the bottom will move around and come out of the dash like it's on a hinge.
I came up with a fix for this if you run into this issue, once again proving my theory that duct tape can fix most any problem.
When the entire vent assembly is out of the dash, take a look at the bottom of the assembly and follow these instructions, created brilliantly in MS Paint:
Use about 6-7 layers of duct tape. Any amount is fine as long as it doesn't come out from behind the vent trim. I did this trick with my dash and my vent has been securely in place ever since. Probably more securely than it was with those cheap ass clips.
Hope this helps someone out!