Help needed concerning custom controls (treeView)

[timtos]

I want to write my own treeview control.

I set
this.SetStyle(ControlStyles.UserPaint, true);
and painted a treeview from scratch.

So far so good.
The problem now is that if I use/ tear the scrollbars
to scroll up and down, some parts of the treeview
are missing/ not painted. The same happens when _clicking_
on the scrollbar to scroll up and down. But the result of
this is often much better.

I´ve tried to override the WM_ERASEBKGND event
but that was a poor try and didn´t work...

Any ideas what that can be and how it can be resolved?
A really BIG thanks in advance.

Greetings,
timtos.