GroupID group_over;    ///< Group over which a vehicle is dragged, INVALID_GROUP if none

	GroupID group_confirm; ///< Group awaiting delete confirmation

	GUIGroupList groups;   ///< List of groups

	uint tiny_step_height; ///< Step height for the group list

	Scrollbar *group_sb;

	Dimension column_size[VGC_END]; ///< Size of the columns in the group list.

	void AddChildren(GUIGroupList *source, GroupID parent, int indent)

	{

		for (const Group *g : *source) {