docs: def hoverMoveEvent( self, event ):
          """
          Tracks whether or not this item is being hovered.
          
          :param      event | <QEvent>
          """
          point = event.pos()
          
          found_key = ''
          found = None
          for key, value, subpath in self._subpaths:
              if subpath.contains(point):
                  found = subpath
                  found_key = key
                  break
          
          if found:
              # update the tooltip
              tip    = self.keyToolTip(found_key)
              if ( tip ):
                  widget = self.scene().chartWidget()
                  anchor = XPopupWidget.Anchor.RightCenter
                  
                  # show the popup widget
                  XPopupWidget.showToolTip(tip, 
                                           anchor = anchor,
                                           parent = widget,
                                           foreground = self.color().darker(120),
                                           background = self.alternateColor())
              
              if ( found != self._hoveredPath ):
                  self._hoveredPath = found
                  self.update()