docs: def _updateViewRect( self ):
          """
          Updates the view rect to match the current tree value.
          """
          if not self.updatesEnabled():
              return
          
          header_h    = self._cellHeight * 2
          rect        = self.uiGanttVIEW.scene().sceneRect()
          sbar_max    = self.uiGanttTREE.verticalScrollBar().maximum()
          sbar_max   += self.uiGanttTREE.viewport().height() + header_h
          widget_max  = self.uiGanttVIEW.height()
          widget_max -= (self.uiGanttVIEW.horizontalScrollBar().height() + 10)
          
          rect.setHeight(max(widget_max, sbar_max))
          self.uiGanttVIEW.scene().setSceneRect(rect)