ReAction/ClassAct on OS3 is no longer developed, the source code is not available and has fallen behind a long way from the OS4 ReAction. So from that perspective, the OS3 ReAction it is a dead-end.
We need to build new applications for OS3 (not just 3.5/3.9) and as a consequence need building blocks to do that.
These building blocks must be expandable into the future when we need additional functionality, so the only solution is to create our own set of gadgets and classes. The InfoWindow Class
is a good example of where we have created a class that shares a common code base across both OS3 and OS4