okay, this is probably a noobish question, but here goes.
What is Alt+B supposed to do? In previous version it was the vertice loop select key, but that has since been changed to Alt+RMB. When i now try pressing (Edit) Alt+B (Edit) it lets me draw a box around part of a scene, and then hides the other parts from view. :o
Once pressed, nothing i have found can be done to go back to your original view.
Is this some funtion which can help organize your work? Just wondering. 
Alt+B just simply allows you to crop or ‘clip’ certian areas of your view so you can ‘isolate’ parts of your scene. I don’t really use it myself, it’s only really for complex scenes with many objects, so you can concerntrate on editing one point of focus. You can escape it by pressing Alt+B again.
Hope that helps,
From Daniel
you mix up your own text…the ALT+B and not RMB lets you go back to same state as you started in 
simple!
I found it very nice for just editing my head mesh. I can clip out the back-of-head vertices and concentrate on the face, from front view, seeing the reference at the back. Very nice and easy.
Thanx for the replies.
ztonzy
you mix up your own text…the ALT+B and not RMB lets you go back to same state as you started in simple!
Lol. My bad. no wonder no one understands me… 
That’s what it is! Alt-B! I was looking for that feature.
Blender’s current hotkey reference still lists Alt-B as the vertex loop select.
so where is the loop select hidden now?
alt-RMB