The UI map control types do not respect the expected positioning rules when within a controls group (i.e. that their positions are given with respect to the position of the controls group).
Control type 101, positioned within a controls group at [0.5,0.5] for testing purposes:
http://i.imgur.com/Tsdl1hd.jpg
Control type 100, positioned within a controls group:
http://i.imgur.com/dvr0SIL.jpg
The exact same config as above, but with a RscText control (type 0):
http://i.imgur.com/wPaVb79.jpg
It also looks as though they are not bound to the controls group region and will simply display wherever they want to.