code: def classifications_combo_box_changed(
              self, index, exposure, exposure_combo_box, edit_button):
          
          # Disable button if it's no classification
          edit_button.setEnabled(bool(index))
  
          classification = self.get_classification(exposure_combo_box)
          self.activate_classification(exposure, classification)
          clear_layout(self.right_layout)
          self.show_current_state()
  
          self.parent.pbnNext.setEnabled(self.is_ready_to_next_step())
  
          # Open edit panel directly
          edit_button.click()
docs: Action when classification combo box changed.
  
          :param index: The index of the combo box.
          :type index: int
  
          :param exposure: The exposure associated with the combo box.
          :type exposure: dict
  
          :param exposure_combo_box: Combo box for the classification.
          :type exposure_combo_box: QComboBox
  
          :param edit_button: The edit button associate with combo box.
          :type edit_button: QPushButton