Thanks for the reply, I did not have a look at that add-on yet, but I did find a solution myself. First off I was being blind and forgot add the "mouseEnabled" feature to the control. Second this is all I had to do to get it to work from within the xml file itself:
Code:
<OnMouseEnter> self:GetNamedChild("BG"):SetEdgeColor(0.4, 0.6, 1) </OnMouseEnter>
<OnMouseExit> self:GetNamedChild("BG"):SetEdgeColor(0.6, 0.6, 0.6) </OnMouseExit>