question: private void highLightBorder ( Graphics g ) { g . setColor ( style . getHighLightColor ( ) ) ; Border border = style . getBorder ( ) ; if ( orientation == JSplitPane . HORIZONTAL_SPLIT ) { int width = border . getBorderInsets ( this ) . left ; g . fillRect ( 0 , 0 , width , getHeight ( ) ) ; g . fillRect ( getWidth ( ) - width , 0 , width , getHeight ( ) ) ; } else { int height = border . getBorderInsets ( this ) . top ; g . fillRect ( 0 , 0 , getWidth ( ) , height ) ; g . fillRect ( 0 , getHeight ( ) - height , getWidth ( ) , height ) ; } }
target:  Paint highlighted borders. Meanot to be used at mouseover.