Sub-folders are shown within their parent by default. If you activate this option, sub-folders are displayed on their own. It looks less nice but it may help if you have a very big folder you want to spread in two columns.
Syb- mappen binne standert te sjen yn har boppelizzende map. As jo dizze opsje ynskeakelje, sub- mappen sille op harsels werjûn wurde. It likjet net moaier mar it kin helpe as jo in grutte map ha dy' t jo spriede wolle oer twa kolommen.