@Override
	public void mouseUp(MouseEvent e, int x, int y) {
		Position p = GfxConstants.getPositionFromXY(x, y);
		if (p.getRow() >= 0 && p.getRow() < GameConstants.WORLDSIZE
				&& p.getColumn() >= 0
				&& p.getColumn() < GameConstants.WORLDSIZE) {

			// check if a tile was clicked
			Unit u = game.getUnitAt(p);
			City c = game.getCityAt(p);

			game.setTileFocus(p);
			if (u == null && c == null) {
			}
		}
	}