Being able to expand all and collapse all folders in the Resources section would be helpful. Also, if we could select a group of folders, click the disclosure triangle to expand and collapse them would be helpful too, this too in the Page Layout section. Like this:
I did a Select All (Cmd-A) and used either the left or right arrow key (on the keyboard) or just select the folders you want to open/close and do the same
Thanks @RussOggi255. That is what I need. It works, but it is a well hidden feature. I just tested that on folders in the finder and that is how it works there, so it must be a standard procedure that I did not know.
I first discovered it in Finder.