Occurs before an end-user performs the operation that leads to raising an Action's Execute event.
The event handler receives an argument of the CancelEventHandler type.
The main entry point of Actions is their Execute event. This event is raised when an end-user performs a predefined operation, specified in different ways for each Action type. For instance, if you add an Action of the SimpleAction type, the Execute event is raised when an end-user clicks the button that corresponds to this Action. See the SimpleAction, ParametrizedAction, SingleChoiceAction, PopupWindowShowAction and ActionUrl classes, for details.
Handle the Executing event to cancel execution of the current Action. For this purpose, set the handler's CancelEventHandler.Cancel parameter to true. In this instance, the ActionBase.ExecuteCanceled event will be raised.