Loren,

You certainly can post your modifications here. Just give the proper attribution to the originator of the code, something like "New Widget class based on Joe Smith's SuperWidget".

While I can't speak for everyone here, I put code in the libraries because I want other to use, modify it, enhance it, and all that stuff. I don't always have the time to update things I've done in the past and I find it very flattering that someone would take the time to improve something I posted. The desire to share the improvements with the community is right in the same spirit that I originally posted stuff from.

An email asking for teh original author's thoughts on your changes would not be out of line, but I don't think you should ask the original poster to test the modifications you have made and then post the stuff as their own.