I've set up the new option as mentioned above and opened a folder where I do grouping with some evaluators. However, the padding does not apply immediately, as you might see in the vid below.
The appropriate option is initially switched on as well as some pixel for left padding. When opening the folder in question and expanding a group, the padding is not active. I expected the files in the group to be padded by 12 pixel on the left side.
However, when cycling the option below "Use left padding..." the indention starts working.
Additonally, with above option still in place, I restarted DO, opened the same folder as above and expand the group again. I still see the same behaviour as described above: not padding.
I can confirm, it now work perfectly well, really like this little enhancement since such little gems do make DO more and more perfect with each release!