Very often I use the tools "Split file" and "Join files" and I have a feature request about "Join files": I would like to see that, after a succesful Join, all fragments are deleted automaticly (Pehaps you could make this switchable on the interface).
Now I have to delete the fragments manually.
If you edit the Join Files menu item (Settings -> Customize Toolbars, then right-click the menu item and choose Edit), then click Advanced, and add @nodeselect to the command, like this:
Join HERE @nodeselect
You can then select the files you want to join, click Join Files, (move the files around in the list if needed) and click OK to join them, as before. But now the files will also remain selected, so you can click Delete if you are happy with the result and want to delete the input files.
If you really want it to be automatic, you can make the command this:
Join HERE
Delete
That will delete the selected files after the join.
Of course, this only works if you're selecting the files in advance. Join Files also lets you open its dialog and then add files to it from various places, which the @nodeselect and Delete command changes won't know anything about.