code: private void updateBorderBasedOnWidth(float width, int side) {
  		useVariableBorders = true;
  		if (width > 0)
  			enableBorderSide(side);
  		else
  			disableBorderSide(side);
  	}
docs: Helper function updating the border flag for a side
  based on the specified width.
  A width of 0 will disable the border on that side.
  Any other width enables it.
  
  @param width	width of border
  @param side	border side constant