Image transparent and a button

Hello,


I have a program in C# that contains a form with one picture box. This
picture box contains two images: One background image and a second
image as a transparent in order to see the first image (the background
image).
The program works well, but there is a small problem that I couldn’t
fix it. When the mouse hover a button (in my case a close button) the
transparent image becomes less transparent. And if we try several
times to hover the close button, the transparent image becomes opaque
and the background image could not be seen any more.

Any answer will be very welcome.

Regards,

Djamila.
.