Wow - thanks borgus. Found the note, and figured out what's going on:
In the classic sense, a crossfade is both an overlap and a fading action. Crossfading overlaps two tracks, simultaneously fading them in different directions: the first track is faded down as the second track is faded up. If you're adjoining two audio tracks, and want to crossfade, then during the transition you're going to have audio playing from both tracks at the same time. You need some "expendable" audio.
There are two ways programs (most, that is) deal with this expendable audio:
1. The user pushes two tracks together, and they will sort of mesh, in effect "crossing" over (or into) one another. Some graphics in these programs even go so far as to make it look like two tracks meshing together; each becomes transluscent, and you can basically see one track laid over the other.
2. The user must remove the expendable bit of audio at the beginning of the second track, as well as the expendable audio at the end of the first track. Then, abut the two tracks together, lay the "crossfade" effect across the two, let the software figure out which bits he/she removed, and fade accordingly.
PD11 can't do either of these things. Which is what the help file means when it says, "the cross transition is not supported..."
However, that's not the clearest way to explain this. The cross transition, as the user wants it to be, is not supported. But there IS a cross transition PD11 will do, after compensating for its inability to figure out those "expendable" audio bits -- fading out the first track early, and pulling in the second track far enough to fade it in.
The help file should say, "the cross transition is not a true crossfade," or better yet, "the cross transition will work the way you want it once you've gotten used to constantly unlinking audio/video, moving the audio track a specific measure to the right, programming a predefined amount of extra time into the beginning of the audio track, adding that same amount to the end of the preceding audio track..."
Major disappointment here.