so it seems a reasonable wild guess that the contact distribution on the coadjoint partial flag variety x is given by the zariski tangent space of the "schubert variety" (not sure whether it actually officially qualifies as one, but it more or less is one) given by "the second most special x/x orientation" ... or something like that... on the grounds that that orientation corresponds precisely in some sense to "the corner heisenberg, minus the exact corner" (or something like that)... though certain annoying "convention mismatches" that i've hinted at make me somewhat less optimistic about this guess than i might otherwise be... anyway, it seems like a good idea to check this guess on the a-series case... and be quite prepared to modify it if it doesn't seem to be working out...

so... in the a-series case the contact distribution has something to do with "moving the coadjoint partial flag in such a way that the point slides along the original hyperplane" ... ??so what sort of bruhat class (or whatever) does this amount to?? ...

hmmm, there seems to be some tricky stuff going on here, and in particular my guess above doesn't seem quite correct ... ???....

what about whether the contact distribution is the zariski tangent space of the supremum of all of the schubert varieties except the most generic?? (or something like that.) it's not clear to me that this is guaranteed to work, because (??among other things??) for all i know the tangent cone might be un-snug in the zariski tangent space, which might be co-dimension 0 ... ??....