code: def showMultiSelectBox(self):
      ## Get list of selected canvas items
      items = self.selectedItems()
  
      rect = self.view.itemBoundingRect(items[0].graphicsItem())
      for i in items:
          if (
              not i.isMovable()
          ):  ## all items in selection must be movable
              return
          br = self.view.itemBoundingRect(i.graphicsItem())
          rect = rect | br
  
      self.multiSelectBox.blockSignals(True)
      self.multiSelectBox.setPos([rect.x(), rect.y()])
      self.multiSelectBox.setSize(rect.size())
      self.multiSelectBox.setAngle(0)
      self.multiSelectBox.blockSignals(False)
  
      self.multiSelectBox.show()
  
      self.ui.mirrorSelectionBtn.show()
      self.ui.reflectSelectionBtn.show()
      self.ui.resetTransformsBtn.show()
  
imports: import gc
  import importlib
  import weakref
  import warnings
  from ..graphicsItems.GridItem import GridItem
  from ..graphicsItems.ROI import ROI
  from ..graphicsItems.ViewBox import ViewBox
  from ..Qt import QT_LIB, QtCore, QtGui, QtWidgets
  from .None import CanvasTemplate_generic
  from .CanvasItem import CanvasItem, GroupCanvasItem
  from .CanvasManager import CanvasManager
label_desc: Use image node_id 13 for calling the Canvas obj's underlying member method code with example usage: obj.showMultiSelectBox() without return types