Returns whether the combo box sets the dropdown button sensitive or not when there are no items in the model.
%GTK_SENSITIVITY_ON if the dropdown button is sensitive when the model is empty, %GTK_SENSITIVITY_OFF if the button is always insensitive or %GTK_SENSITIVITY_AUTO if it is only sensitive as long as the model has one item to be selected.
2.14
See Implementation
Returns whether the combo box sets the dropdown button sensitive or not when there are no items in the model.