how to reduce form flick?

I have a tab, which has an image in it. When an user double click, I need make the panel in that tab invisible and show another image (within the same tab). I finished it. but when I make the panel invisible and image visible, the screen flicks, and it shows a black background tab for a about 1/2 or maybe 1/4 seconds.

Double buffer for the form does not fix the problem. any other suggestions? Is there a way that I can force a control to be on the top of another control in the program?

thanks

bear