#50 several problems with home page doc links

[Anonymous]

1. the float tag allows it to fall out of the page
border, so it stretches down a little funny
2. it doesn't truncate the lists of documents to
something reasonable (ie 5 documents per heading) and
instead shows every document in a long list.
3. the document popularity is a bad calculation, since
it determines the documents age by taking the
difference between the date created and date modified,
instead of taking the difference between the date
created and now.