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.