code: def setCheckable( self, state ):
          
          self._checkable = state
          
          # need to be editable to be checkable
          edit = self.lineEdit()
          if state:
              self.setEditable(True)
              edit.setReadOnly(True)
              
              # create connections
              model = self.model()
              model.rowsInserted.connect(self.adjustCheckState)
              model.dataChanged.connect(self.updateCheckedText)
          
          elif edit:
              edit.setReadOnly(False)
          
          self.updateCheckState()
          self.updateCheckedText()
docs: Sets whether or not this combobox stores checkable items.
          
          :param      state | <bool>