Skin: 3 vertical columns

[verbatim]

http://www.roundcubeforum.net/index.php/topic,5777.msg23119.html#msg23073

It appears this feature has been mentioned before. It would be great to add it to the Classic and Larry skins.
In Settings > Preferences > Mailbox View, it would be great if there were an option to display as either panes stacked (as current) or three vertical panes (see attached image)

[LuckyCoolFella]

Hi, is there a way to have this 3-column view?