code: public void setExtraHeight(int cell, float height) {
  		if (cell < 0 || cell >= cells.length)
  			return;
  		extraHeights[cell] = height;
  	}
docs: Sets an extra height for a cell.
  @param	cell	the index of the cell that needs an extra height
  @param	height	the extra height
  @since	2.1.6