private void openAreaTile(int aTile)
	{
		final byte openId = mField.getMasks().getOpen().getId();
		final int x = Tile.getX(aTile), y = Tile.getY(aTile);
		mField.setMask(x, y, openId);
		TileValue tileValue;
		TileSet border = mField.getBorderOf(x, y);
		for (int tile : border)
		{
			tileValue = mField.getTileValue(tile);
			if ( !tileValue.isEmpty() && !tileValue.isBomb()) mField.setMask(tile, openId);
		}
	}