Added buttons to collapse or expand ALL groups.

(cherry picked from commit bb6b96e8663b5cb3da87d8473e70e373a36b3997)

src/widgets/group_widget.h

@@ -32,6 +32,8 @@ enum GroupListWidgets {
 	WID_GL_DELETE_GROUP,             ///< Delete group button.
 	WID_GL_RENAME_GROUP,             ///< Rename group button.
 	WID_GL_COLLAPSE_EXPAND_GROUP,    ///< Collapse/expand group button.
+	WID_GL_COLLAPSE_ALL_GROUPS,      ///< Collapse all groups button.
+	WID_GL_EXPAND_ALL_GROUPS,        ///< Expand all groups button.
 	WID_GL_REPLACE_PROTECTION,       ///< Replace protection button.
 };