public void dropRoster(Integer rosterID, javax.swing.TransferHandler.DropLocation dropLocation) {
		TripComponent tc = tripList.getSelectedValue();
		if (tc == null) {
			tc = new TripComponent (MainWindow.tripDB.add ( targetDay.getTime() ));
			tripListModel.addElement (tc);
		}
		tc.getTrip().addRoster(MainWindow.rosterDB.getRosterByID(rosterID));
		updateGroupIndex();
		tfRoster.setText(MainWindow.tripDB.getRosterCount(targetDay.getTime()) + "/" + availableRosters);
		tripList.invalidate();
		tripList.repaint();
		rosterList.repaint();
	}