When mail list options invoked by button in leftmost header column, and set of visible columns has been changed, changes irreversably override global settings defined in "main.inc.php".
F.e. if in global config defined
$rcmail_config['list_cols'] = array('flag','attachment','subject','from','date','size');
after changes in "List options" attachment mark (paperclip) moves rightmost. No further manipulations, except direct editing of
mysql.rcube.users.preferences field cures that.
N.B.
It's lack of 0.4b prefix in forum message form
