sig
type t_env
val button_one_press_on_graph : ViewGraph.SigCb.t_env -> unit
val button_two_press_on_graph : ViewGraph.SigCb.t_env -> unit
val button_three_press_on_graph : ViewGraph.SigCb.t_env -> unit
val button_one_press_on_node :
ViewGraph.SigCb.t_env -> ViewGraph.t_node -> unit
val button_two_press_on_node :
ViewGraph.SigCb.t_env -> ViewGraph.t_node -> unit
val button_three_press_on_node :
ViewGraph.SigCb.t_env -> ViewGraph.t_node -> unit
val enter_node : ViewGraph.SigCb.t_env -> ViewGraph.t_node -> unit
val leave_node : ViewGraph.SigCb.t_env -> ViewGraph.t_node -> unit
end