How to collapse all folders in list view

If you search on this topic, there are many discussions about it without a real solution. The challenge is the following: you have a list view of many folders, some of which are expanded, and some are not ( to expand/collapse a folder you click on the little triangle by the name of the folder ). Lilke many users on the apple discussions I wanted to collapse all of them with one action instead of clicking on each folder individually.

I found a solution on superuser.com: first, in the list view, select all with command-A, and then press Command-(left arrow). To expand all, do Command-A followed by Command-(right arrow).

I hope that helps, and my apologies if this solution has been given before, but I didn't find it with my 5 minute search. 🙂