code: def setViewMode( self, state = True ):
          
          if self._viewMode == state:
              return
              
          self._viewMode = state
          if state:
              self._mainView.setDragMode( self._mainView.ScrollHandDrag )
          else:
              self._mainView.setDragMode( self._mainView.RubberBandDrag )
              
          self.emitViewModeChanged()
docs: Starts the view mode for moving around the scene.