能使得視窗form半透明效果

procedure   TForm1.FormCreate(Sender:   TObject);   
var   l:longint;   
begin     
  l:=getWindowLong(Handle,   GWL_EXSTYLE);     
  l := l Or WS_EX_LAYERED;      
  SetWindowLong   (handle,   GWL_EXSTYLE,   l);   
  SetLayeredWindowAttributes   (handle,   0,   180,   LWA_ALPHA);   
end