Hook to change display style of secondary groups

[Steffen Loos]

Hi,

I need to change the style of displaying the secondary groups for members in AdminCP. Because we are using a bunch of groups for our forum, the list-box is not very usefull for us and also not fail-safe when setting/changing groups for members (which often occurs). For this I want to change the style to check-boxes (as for example vBulletin does).
I did some test with hooks, and I managed to write a code- and template hook for showing simple messages. But I cant find the entry for changing the style of the list-box of the secondary groups. 

I would be very happy to get a little hint how to achieve this... Does anyone has an idea?

Thanks in advance,
Steffen