c# - How to remove black screen on windows form -

i have windows form.

in form have loaded panel.

when resize form non client area becomes black.

how remove black screen.

i have tried in many ways passing parameter, double buffer.

protected override createparams createparams {         {         createparams cp = base.createparams;         cp.exstyle |= 0x02000000;         return cp;     } }