Occurs before the built-in event dialog is shown. Return false or call event.preventDefault() in order to cancel event and prevent the built-in dialog to be shown.

var instance; // Type: options
instance.beforeEditEventDialogShow = function(e, data) { };

beforeEditEventDialogShow = function ( 
   e : jQuery.Event,
   data : IBeforeEditEventDialogShowEventArgs
) { };