I found a solution in Codegears quality central:

"TGraphicControl descendants invisible in frames with XP Manifest"
http://qc.codegear.com/wc/qcmain.aspx?d=3850

> I have a painting problem with AutoLabel's under Vista.
> They don't paint the first time a dialog is showing.
> After resizing most of them paint then.
>
> Does somebody know a fix for this problem?
>
> Andreas
>