Send the file posted to the tiddlyweb server back to the browser.
First stab at tiddlywebplugins.reflector, a reflector plugin idea from Ben Gillies:
Post a file to the reflector and it gets returned to the browser with the content-type it was given.
If you put the sending form in an iframe, then you can gather up the content of the iframe and give it to tiddlywiki for use in the import routines.
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Hashes for tiddlywebplugins.reflector-0.9.tar.gz