In the message details pane it would be nice if, for fuzzy messages, the old string (which appears commented in the po file if you use a text editor) was visible.
This would allow a translator to compare the new string with the old string and take better decisions on how to update the string.

It may seem not much useful, but it is.
I often have to double-check what really changed in a fuzzy string, as it's not necessarily obvious, either because it's a minor change or a typo fix or because the translation was quite free and not literal.