I want to keep my cursor's vertical position when page up (Ctl-U) or down (Ctl-D). This is particularly useful when I am in a long python function and want to figure out block structures by indentation.
Current behavior when I page down:
if foo:
xxx = yyy
^ <-- cursor was here before page down
... many content in between ...
while bar:
xxx = yyy
^ ^ <-- cursor jumped here after page down
^ <-- I want it to stay here