question: public boolean isCompletelyCollapsed ( ) { if ( collapsedUnder == null ) { return false ; } if ( Math . abs ( positionX - collapsedUnder . positionX ) < COLLAPSE_TOLERANCE && Math . abs ( positionY - collapsedUnder . positionY ) < COLLAPSE_TOLERANCE ) { return true ; } return false ; }
target:  Say if the node is collapsed, and has reached the position of its parent.