(I mean collapse all and when you reopen the root node every folder/subfolder is really closed.)
Sound strange but lots of people are asking for this simple feature (present on Eclipse) because on large projects it's a pain having to bring order closing every single sub-node. Unfortunately, if you collapse a node it only hides the children and when you click it again all the children are still there, in the same status as before.
The Netbeans team solved the problem on some panels but few developers know that because it's still undocumented. I track it down rooting everywhere and finally finding the info in the Netbeans bugzilla website where I discovered this black magic formula:
Open the desired window (es CTRL+1 per Project)
Do it and you'll se the Collapse all item in the menu.
On that info I then discovered a simpler way by myself:
you only have to right click in the empty space before the arrow!