In the Gambas IDE, when you select any control on a form, in the Properties dialog you should notice a Group property that doesn't correspond to any documented property of that control. This special pseudo-property allows you to assign control groups. Essentially, when that control is created at runtime, it will be treated as though you had created it in code like so:
myControl = NEW ColumnView(ME) AS "myGroup"
and its event handlers must be named like so:
PUBLIC SUB myGroup_Click()
You can refer to the control that generated the event with the LAST keyword, or you can assign a Tag to each control to differentiate them that way.