Adds translucent bars to the top and bottom of the viewport, which indicates the previous viewport position when the page is scrolled. This tool will prevents you from getting lost when you press the Page Up/Down keys.
This is a script I salvaged off the old http://userscripts.org/users/mstm account. I could not find the original owner; if this is your code, let me know.
Not working yet.
Seems to work OK.
