A nice to have wish for us, would be to allow creation of a new Category directly for the 'New File' page. A user can name the file, browse to find it, add comments, set the assignees and then realize they don't have the correct Category. If the user is not thinking they will not submit, but rather go back to 'Manage Categories' to add the new one. They will have lost the date, because there is no persistence on the form.

To add an input field that allows creation of the Category on that 'New File' screen would be a nice to have.