Can't create "Exclude list" if the alignment is in read-only directory

Scenario:

1. Move "COI.aln" to read-only directory.
2. Open the moved "COI.aln".
3. Click "Show/hide Exclude list"
   Current: No Exclude list table. If you click on the sequence and add it to the exclude list, this sequence just gone. Can't save, can't change directory (the button is disabled):
   

Expected: you can't write exclude-list file to the read-only directory, but you can save it somewhere else