Remove border from popup button More options

Hi all,

Originally, I posted this post in
microsoft.public.dotnet.languages.csharp.
I was offered to try get answer here.

I am writing my app in C#.

I have button which its flatstyle is popup. The problem is that it
has
border when user doesn't
move the mouse on the button. How can I remove the border that only
when the user moves the mouse cursor on that button, it sets border
so
it looks like 3d?

The problem is that the popup button doesn't look popup in its current
graphic.

Thanks,
Eran.

.