scrollbar position not relate with arrow button

[scummyman]

Hi ! You plugin very helpful, but
When I dragging scrollbar to middle of slide (or anywhere else) and then I press arrow button,Scrollbar alway jump to current position.

Ex. I start at first image,and then I dragging to last image,I will can't press left arrow button(because current position at first image),if I press right button slide will jump to second image.
How to fix it?

Hope you understand my question.
ps.Sorry for my english.
Thank!!