Looks like you can't according to this similar question. So I figured there's two options.
1. Turn off Aero
2. Get rid of the border
In my case I didn't need the border so I used SetWindowLong
to remove it
var style = GetWindowLong(handle, GWL_STYLE);
style &= ~(WS_CAPTION | WS_THICKFRAME | WS_MINIMIZE | WS_MAXIMIZE | WS_SYSMENU);
SetWindowLong(handle, GWL_STYLE, style);