...
Type 
   TForm1 = class(Tform)
	...
   Private
	procedure SpoolerStatus(var Msg : TWMSPOOLERSTATUS);
        message WM_SPOOLERSTATUS;
    	...
  Public
    ...
 end;

....

procedure TForm1.SpoolerStatus(var Msg : TWMSPOOLERSTATUS);
begin
  Lable1.Caption := IntToStr(msg.JobsLeft) +
                    ' Jobs currenly in spooler';
  msg.Result := 0;
end;
...