When you look at a question, off to the right is the list of tags on it, including the number of tags that exist in the database for each of them (maybe off by some yet-to-be-cached amount).
When I go to edit that question, the tags don't show to the right. This is one of the things I use when editing to determine whether a tag is worthy of being there (just one of the things). Please have the question-specific tag list show when editing.
Right now I have to open a new window to relook at the tag list, or backup and start over.
Here's a screenshot of how I'd like it to look.