function doublekey(key:integer):boolean;
 var
  time:integer;
 begin
  if key<>0 then
   begin
    time:=getrelativetimems;
    if (getrelativetimems-time<500) and (getkeyclicked=key) then
     doublekey:=true;
    else
     doublekey:=false;
   end;
  end;