Used to specify the style of the expanders drawn by a GtkTreeView.
Value | Symbolic name | Description |
| 0 | Gtk::EXPANDER_COLLAPSED | The style used for a collapsed subtree. |
| 1 | Gtk::EXPANDER_SEMI_COLLAPSED | Intermediate style used during animation. |
| 2 | Gtk::EXPANDER_SEMI_EXPANDED | Intermediate style used during animation. |
| 3 | Gtk::EXPANDER_EXPANDED | The style used for an expanded subtree. |