There are three ways to tell if Xojo code is using API 1 or 2.
1.) - Many of the property, method and event names of an object or control differ between API-1 and API-2. There are too many differences to list here.
2.) - Look at the “Super” class of an object or control type and see if it has a prefix of “Desktop”, “Web” or “Mobile”. These are API 2 objects and controls (and therefore use API 2 names and syntax).
If the object type does not have one of these prefixes, then it’s API 1. There are exceptions of course, like the Timer object and Thread class, and others…
3.) - Under the Project > Analysis Warnings… menu, ensure the following (highlighted) options are turned on. These will help pinpoint where API 2 syntax or new property/method/event names should be used.