It occurs due to the functional limitation of the jog dial
and the specification of the screen saver.
The jog dial has the function to generate specific events such
as the scroll function on active windows.
The jog dial, however, is not such an input device as a
keyboard and a mouse.
On the other hand, the screen saver is designed to start or
stop by detecting the operation of the keyboard or the mouse.
As it cannot detect the input from the jog dial, therefore, it
appears irrespective of the jog dial operation.
"JogScrLock", which is one of the screen savers, has been
designed to stops its function by detecting the operation of
the jog dial. Only this screen saver disappears in response
to the operation of the jog dial.
Even when you select "JogScrLock", it starts regardless of
the operation of the jog dial as Windows monitors the input
devices as far as the start of the screen saver is concerned.