Will unset a previously set model (if applicable). If model is null,
then it will unset the model.
Note that this function does not clear the cell renderers, you have to
call gtk.cell_layout.CellLayout.clear yourself if you need to set up different
cell renderers for the new model.
Sets the model used by combo_box to be model.
Will unset a previously set model (if applicable). If model is null, then it will unset the model.
Note that this function does not clear the cell renderers, you have to call gtk.cell_layout.CellLayout.clear yourself if you need to set up different cell renderers for the new model.