Found it. I had this situation: in a groupbox I had 3 control sets, each of them consisting of 2 radiobuttons, which had to take the value of 3 global boolean vars. Only the last control set got checked. That made my think about radio buttons in a groupbox.
What I didn’t know is that in a groupbox apparently only ONE radiobutton can have a TRUE value EVEN if they belong to different control sets. My thought was to put them in different control sets to overcome this problem…
Put each set on a Rectangle or Canvas on top of the groupbox. Canvas is invisible, but it might be good to have a visual separation between the groups.