PageUp / PageDown should allow scroll instead of zoom

[valir]

First of all, thanks for this great tool!

I have here a very large graph and I'm trying to scan it. Usually, PageUp/PageDown come-in very handy in such situations. But xdot maps these to ZoomIn/ZoomOut, leaving me to only use arrows, or the mouse, which is suboptimal in my case.

Please bind to PageUp/PageDown keys to scrolling a whole window's height up or down. Thanks,