Hi P.,
May be not what you are asking for, but a workaround I use to edit lists in a field.
I enter (or copy/paste from a list field) all values in the text area of the tiddler containing that list.
So it will look like (place every value at a separate line for readability):
listvalue1
listvalue2
listvalue3
listvalue4
listvalue5
...
listvaluex
In case you want to hide these list values in view mode, you can make an HTML comment of it:
<!--
listvalue1
listvalue2
listvalue3
listvalue4
listvalue5
...
listvaluex
-->
Now you can edit and/or reorder the list values in the text area.
When you are ready, just copy these set of list values into the list field. and that's it.
Cheers,
Ton