private void changeTrack(int x){
		int tempBid=(x-10)/70;
		System.out.println("Dans ChangeTrack : temp ="+tempBid);
		if(selectedBid==tempBid){//cancel the selected bid
			selectedBid=-1;
		}else if(selectedBid==-1 && tempBid<bidding.getTrack().length){ //select a family
			selectedBid=tempBid;
		}else if(tempBid<bidding.getTrack().length && bidding.getTrack()[tempBid].getBid()==bidding.getTrack()[selectedBid].getBid()){//chage the order
			bidding.interchange(selectedBid, tempBid);
			selectedBid=-1;
		}
		repaint();
	}