Can Execute Changed Event
Occurs when changes occur that affect whether or not the command should execute.
public: event EventHandler ^ CanExecuteChanged;
event EventHandler CanExecuteChanged;
member this.CanExecuteChanged : EventHandler
Event CanExecuteChanged As EventHandler
Normally, a command source calls CanExecute on the command when this event occurs.
Normally, if the command cannot execute, the command source disables itself.