Scrolling through the line-by-line diff is a primary requirement for most editors and it works well. However, doing so using the keyboard can be a little difficult as scrolling depends on which element is in focus. If I click on the diff-panel's scroll bar and then press the up or down keys on my keyboard, I am able to scroll fine. However, if this scroll bar does not have focus, my up-down arrow presses usually affect something else like scrolling through the default summary text field's history.
Another drawback of having to click on the diff scrollbar to switch focus is that other short-cuts like F10, etc., also stop working.
It will be useful if AWB could provide keyboard short-cuts (e.g., CTRL + up/down) that are dedicated to scrolling through the diff window. This will make the application more keyboard friendly.