set_mode
Description:
Sets the `GtkSizeGroupMode` of the size group.
The mode of the size group determines whether the widgets in the size group should all have the same horizontal requisition ( gtk_size_group_horizontal) all have the same vertical requisition ( gtk_size_group_vertical), or should all have the same requisition in both directions (gtk_size_group_both ).
Parameters:
| this |
a `GtkSizeGroup` |
| mode |
the mode to set for the size group. |