I'd like to offer a patch which not directly fixes but actually prevents the bug. As far as I understand after learning the code, the first column (Name) is a kind of exclusive thing which is not even intended to be moved, so the logical step is to fix the column at the place. The patch involves a hook which is probably not the most elegant way to do the work, but I couldn't find any better solution.
Please, ignore this ticket. Description inaccurate.
Here is another ticket with the same content but more accurate description.
https://sourceforge.net/p/jedit/patches/603/