I think a keybinding would be very useful (unless there's some way to bind scripts to key presses in the viewer?). The key binding really seems like it should already be there inside the viewer window but we just don't know what it is.

If it doesn't exist and it gets added at some point. I humbly request that the binding it also works for bucket datasets (as the index rocker in the viewer doesn't work for them). As far as I know you have to open up the define overlay pane and pick from a menu to change the underlay. Often I'll fiddle with the window layout, open up a time graph viewer for no other reason than to stick my mouse in there and use arrow keys. You can also refit a time axis onto a bucket dataset so I can do this. It just seems impure ;)

--judd