code: def showPopup(self):
          
          if not self.showTreePopup():
              return super(XOrbRecordBox, self).showPopup()
          
          tree = self.treePopupWidget()
          
          if tree and not tree.isVisible():
              tree.move(self.mapToGlobal(QPoint(0, self.height())))
              tree.resize(self.width(), 250)
              tree.resizeToContents()
              tree.filterItems('')
              tree.setFilteredColumns(range(tree.columnCount()))
              tree.show()
docs: Overloads the popup method from QComboBox to display an ORB tree widget
          when necessary.
          
          :sa     setShowTreePopup