code: def __init__(self, parent=None):
      QtWidgets.QComboBox.__init__(self, parent)
      man = CanvasManager.instance()
      man.sigCanvasListChanged.connect(self.updateCanvasList)
      self.hostName = None
      self.updateCanvasList()
  
file_path: pyqtgraph/pyqtgraph/canvas/CanvasManager.py
imports: from ..Qt import QtCore, QtWidgets
  import weakref
label_desc: Use image node_id 1 to create a new CanvasCombo object from inherited base classes: QtWidgets with example: obj = CanvasCombo(parent)