S60 - CAknListBox and Background Problem

Hello everyone,

i've got the problem, that i use a CAknSingleStyleListBox on half the screen size
(Width = Rect.width, Height= rect.height/2). The theme background is shown, but
the list box always paints some dots, which should normaly be shown vertically and
at the bottom horizontically (Means that only a view dots are painted).

Anyone has a clue to stop that ugly drawing behaviour of the ListBox?

Thank you for replys in advance.
Jochen