Control refuses to redraw correctly (UltraTabManager). Inval

We have this UltraTabManager with some tabs, all which contain lots of controls. We have bound both SelectedTabChanged AND SelectedTabChanging to events.

Lets start with "changing": It checks some stuff, if everything is correct, it loads and does a LOT of stuff (takes approx 0.5 sec). If it is not it cancels.

Doing only this, everything works perfectly except 1 thing: It wont redraw after it changed tab and did all that stuff, if I resize the window/change tabs to revalidate it, it redraws correctly.

This made me try adding "THIS-OBJECT:Invalidate()" and "THIS-OBJECT:TabManager:Invalidate()" to SelectedTabChanged, so it redraws it after it has been changed. This does not seem to work at all.

THIS-OBJECT in this case is a custom control in a windowcontainer, I have also tried calling the windows invalidate with "THIS-OBJECT:Root:WindowManager:Window:Invalidate()", but that does no effect at all.

Same result in both OE10 and OE11. I understand if this is not a pure Progress-question since its regarding an Infragistics control, but I would still appreciate any help. Also we had problems with redrawing when we tested OE10 .NET on an XP-machine, pretty much nothing wanted to redraw correctly. That makes me suspect that progress software MIGHT have something to do with it. Using Windows 7, development machine is currently OE10 (so it'd be way easier to test in 10 and not 11 atm).

Thanks in advance