1. View the backlog for a board.
2. click-and-hold an issue (i.e. to drag it to a new position in the backlog).
3. Try to use mousewheel or keyboard (pgup/pgdown/home/end) to navigate the backlog.

Expected behavior:
These should work just like they do when not 'dragging' an issue

Actual behavior:
They don't work at all.

Impact:
User is forced to bump-scroll the issue, which is very frustrating. This is made much worse by JRA-60336.