Drag n Drop between files with different custom columns

Description

Dragging one or more entries from one Mori file to another doesn't work if the custom columns are different in the two notebooks. It starts to work. The gui changes as if to accept the drop. But nothing more happens. Then the insertion marker/outline gets stuck and nothing works without closing the file. Opening again fixes it, but the new entries are not copied.

Copying and pasting doesn't work either. It pretends to and doesn't get stuck, but nothing happens.

I think this is a difficult problem because the custom columns are different in the two notebooks. So how do you handle that case? Just ignore the columns that don't exist? But trying to do it halfway and getting stuck in a weird state isn't good.

It works fine if the columns are the same.