question: private Double clickDistance ( Node node , final float x , final float y ) { return clickDistance ( node , x , y , node . isTagged ( ) ? DataStyle . getCurrent ( ) . nodeToleranceValue : DataStyle . getCurrent ( ) . wayToleranceValue / 2 ) ; }
target:  Calculates the on-screen distance between a node and the screen coordinate of a click. Returns null if the node was outside the click tolerance.