Picturebox - Drawing Problem

Question

hi,
i have a big problem. i`ve made a button control with the Picturebox. I drawing a simple Picture onpaint. When I´m hovering i change the alpha value of the picture and draw again when mouseleave.Now i have many ownderdrawn buttons. when i clicked one of them then deselect all other buttons and select my current button. i have this code:

http://bitbin.it/7YfzYrrP