reduce available frame by scroller width for alternateZoomToFit action only when the scroller should be shown
reduce available frame by scroller width for alternateZoomToFit action only when the scroller should be shown

JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim