Collapsing menu's in derma

If i have two collapsable menu’s, is it possible to make one move down if the other is open? By this i mean if i have one with a:
SetPos( 140, 175 )
and another with:
SetPos( 140, 200 )
could i make the second one add say 100 to it’s Y pos whenever the first is open; so
closed = SetPos( 140, 175 ) AND SetPos( 140, 200 )
open = SetPos( 140, 175 ) AND SetPos( 140, 300 )

EDIT: Ok after checking the lua wiki, i came up with
DCollapsibleCategory.GetExpanded( )
But i don’t know what this returns. (E.g. ‘1’ or ‘true’ etc) So new question; i need to know what this function returns.

Edit 2: Ok still don’t know what it returns but aparently it works with just if DCollapsibleCategory.GetExpanded( ) then -blahblahblah- end