An option to have autoscroll like in Firefox (when it is enabled). Click with the middle mouse button anywhere on the document, a symbol like this is displayed:
Move the mouse up or down, and the screen starts scrolling. The farther the mouse pointer is from the symbol, the faster the autoscroll: from really slow (a few pixels per second) to blazing fast (dozens of pages per second). Click again anywhere (either with middle or left button) to stop autoscrolling.
If instead of clicking with the middle mouse button, the user clicks and drags up or down, the same thing happens, only autoscroll is stopped when the middle mouse button is released.
It is flawlessly implemented in Firefox, including Firefox’s built-in PDF viewer, which is otherwise inferior to Okular in every way (in my opinion), apart from having his feature.
I would like this feature to be an option in the settings, disabled by default, so that current behaviour of middle click (zoom) is not affected for users who prefer it this way.