val day_selected : ([> `calendar ], unit -> unit) GtkSignal.tval day_selected_double_click : ([> `calendar ], unit -> unit) GtkSignal.tval month_changed : ([> `calendar ], unit -> unit) GtkSignal.tval next_month : ([> `calendar ], unit -> unit) GtkSignal.tval next_year : ([> `calendar ], unit -> unit) GtkSignal.tval prev_month : ([> `calendar ], unit -> unit) GtkSignal.tval prev_year : ([> `calendar ], unit -> unit) GtkSignal.t