Hi John. I, too, would find it useful to be able to extend the time axis.
On some of my charts, I'd like to be able to see when trend lines will intersect, and so forth.
Edit: There are times I'd like to be able to extend the price axis either up or down, for the same reasons.
Like you, I've used my ruler, or like MechanicalMethod suggests, I've copied into a graphics program and then copied and pasted the time scale.
It would be a nice little feature to see added, someday.
Cush