From Xojo Documentation
| This event is only available on the macOS platform.
For cross-platform compatibility, use ＃If...＃Endif with the Target... specifiers to make sure you will not attempt to use this event on an incompatible platform.
An AppleEvent has been received.
Intrinsic AppleEvents, such as "aevt/odoc", "aevt/quit", and "aevt/pref", are passed to this event handler first. If you return True, the default behavior will no longer take place. For example, if you return True for the "odoc" event, the OpenDocument event will not fire.