On the right side the user can drag the vertical sliders to the desired position of compare frame.
Unfortuantely these sliders are very small.
Can these sliders be made at least 1 or better 2 pixels wider?
This would required not so much concentration when positioning the mouse over it.
There is no setting to increase slider width. Unless developer of compare plugin think it needful.
But you can use any of the slider of two compared windows. With these, slider of Navigation window also moves.
You can use Ctrl+Pageup, Ctrl+Pagedown, Ctrl+Shift+Pageup and Ctrl+Shift_Pagedown for different movements in compared result.
Sliders (I think you mean the black borders of the Navigation bar) are there just to indicates which portion of the file you are currently looking at. But you move in the file by clicking anywere in the Navigation bar area. Try to click somewhere on this area and, without releasing the mouse button, move you mouse up and down.