WAI-ARIA 1.0 Authoring Practices - Spinbutton Keyboard Interaction

According to the WAI-ARIA 1.0 Authoring Practices, spinbuttons should adjust
the value when the user presses the left or right arrow keys. However, this
makes manually editing the value very difficult since you can't move the
cursor between the existing characters. Even the dojo example linked to from
the Authoring Practices doesn't implement the left/right arrow handling.
We're currently creating a spinbutton control in jQuery UI and we are also
intentionally leaving out the handling for left and right arrow keys.

Due to the existing implementations and decreased usability when
implementing this feature, I suggest that this be removed form the authoring
practices.