If mp3tag for some reason fails do save tag data to a media file, a temporary copy of the media file is left and not deleted.

To reproduce:

1. run mp3tag in a given directory
2. open a media file in this directory with a second application, f.e. winamp or ultraedit
3. change the tag data of the file
4. when attempting to save the tag data, a modal dialog will popup informing you that the file cannot be opened for writing
5. choose ok and open the directory in the browser

-> You'll find an additional tmp file in the directory which must be deleted manually. Otherwise it will stay there forever.

-u302320

Please elaborate where is the buggy behaviour in your list?

DD.20110512.0929.CEST

-> You'll find an additional tmp file in the directory which must be deleted manually. Otherwise it will stay there forever.

Do you think it is ok to waste space on the user's hard disk without any reason?

If mp3tag is able to diagnose the problem and show a dialog it should also be able to delete the self-created tmp file afterwards.
-u302320

Yes, this is true. The .tmp file is left behind... This is especially an issue if the file happens to be a 2GB to 4GB .mp4 file...

As far as I know dows the tmp-file contain all the modifications written by mp3tag. You can now choose whether you want to delete the old unmodified file manually and rename the tmp file or apply the changes all over again.
I think that mp3tag treats the data entered by the user with a lot of respect.