code: def updateCanvasList(self):
      canvases = CanvasManager.instance().listCanvases()
      canvases.insert(0, "")
      if self.hostName in canvases:
          canvases.remove(self.hostName)
  
      sel = self.currentText()
      if sel in canvases:
          self.blockSignals(
              True
          )  ## change does not affect current selection; block signals during update
      self.clear()
      for i in canvases:
          self.addItem(i)
          if i == sel:
              self.setCurrentIndex(self.count())
  
      self.blockSignals(False)
  
file_path: pyqtgraph/pyqtgraph/canvas/CanvasManager.py
imports: from ..Qt import QtCore, QtWidgets
  import weakref
label_desc: Use image node_id 2 for calling the CanvasCombo obj's underlying member method code with example usage: obj.updateCanvasList() without return types