Painting on transparent background multiple times

[C# Programming]

I have a panel with transparent background, that I want to paint on multiple times. It paints alright the first time, but each time after that the drawing gets thicker. This problem is only with transparent backgrounds, drawing anything on it multiple times will make a drawing thicker on each painting event.

Any ideas how to overcome this problem?
modified on Sunday, September 12, 2010 8:10 AM