typedef void __fastcall (__closure *TIdleEvent)(System::TObject* Sender, bool &Done);
TIdleEvent is the type of event handler that perform actions when the application is idle.
Sender is the object that receives the event notification. Typically, this is the application object.
Done indicates whether the event handler has finished its background processing.
If the event handler exits when Done is true, all action components are then given a chance to update themselves and, on Windows, the application yields control to Windows until a new message appears in the application's message queue. When Done is false, any action components in the application are not allowed to update themselves when the event handler exits and, on Windows, the application does not explicitly yield control to the operating system.