c# - Transparent panel can't receive WM_NCHITTEST -

in c# winform project, put panel in form. panel's backcolor same form's transparencykey, looks 'transparent'.

i want form moved when clicking/dragging inside 'transparent' panel. override panel's wndproc below:

public class unclickablepanel : panel {     protected override void wndproc(ref message m) {         if (m.msg == 0x84) {  // wm_nchittest             m.result = new intptr(-1);             return;         }         base.wndproc(ref m);     } } 

in opinion, panel returns "-1"(transparent) , form can handle mouse down/up/move events.

it works fine in win7 aero theme. if win xp or win7 + basic theme, panel can't receive wm_nchittest @ all. click through form.

any solution or workaround?