Script Editor Library

The Script Editor (AppleScript) has a convenient window showing many of your applications, standard additions, and a few others. Is it possible to add to this list? I’d like to add a few other OSAXen and some faceless processes with dictionaries (like the GrowlHelperApp).

I think it should see those automatically.

Do you mean the Library? You can add apps to that using the + button at the top left. Press the button and navigate to the app you would like to add.
You can remove items using the - button.

It doesn’t see OSAXen automagically, but you can navigate to them and select them for entry in the Script Editor Library Panel

I got the OSAXen in that way, but it misses some scriptable faceless apps like “GrowlHelperApp” that can’t be navigated to in a standard file dialog.