Ok, so here's what's up with the syntax checking:

tabnanny sends the output to stdout.  Less than ideal, but very workable.

tabnanny only checks indentation errors.

I figure if this is worth doing, it is worth doing whole hog.

What I am looking at doing now, is simply running "compile", then grabbing the output, and parsing that.

Would that miss anything that tabnanny picks up?

Apparently yes.  The solution was to hack tabnanny to return a result string, and run that after running compile too.

Hm, i tried this already with SPE - Stani's Python Editor.

I couldn't find anything, tabnann find, what
isn't found by the python compile command.

I've found that tabnanny can find mixed indentation errors, such as
->def func:
-> x = 1