The mode of the size group determines the directions in which the size group effects the requested sizes of its component widgets.
Value | Symbolic name | Description |
| 0 | Gtk::SIZE_GROUP_NONE | Group has no effect. |
| 1 | Gtk::SIZE_GROUP_HORIZONTAL | Group effects horizontal requisition. |
| 2 | Gtk::SIZE_GROUP_VERTICAL | Group effects vertical requisition. |
| 3 | Gtk::SIZE_GROUP_BOTH | Group effects both horizontal and vertical requisition. |