For the print mode, it just draws the current page as a normal image.  The user can right click & save it as a PNG image at the current zoom level, adjust the zoom, navigate 1 page at a time.  

The mane problem was handling mouse wheel zooming when the scroll bars were enabled.  It has to set new scrollbar positions in addition to computing a new X & Y from the previous scrollbar positions.  Another problem was indicating the current zoom level.  It was decided to just not support mouse wheel zooming in viewer mode, for now.  It's supposed to just save a PNG image.