how tie .net form the prefiltermessage()?

i'm filtering messages form prefiltermessage this:

print("code sample");

 open bool prefiltermessage(ref summary m) 
 {
     (m.msg == wm_keydown && (int)m.wparam == vk_escape)
     {
         this.close();
         relapse true;
     }
     relapse false;
 }

print("code sample");

but matter form closes wholly initial time. after reopening form won't tie anymore dire esc.

how i accomplish this?

thanks