gistfile1.txt

    //prefix is image path of viewer
        var prefix = opts.prefixUrl;
        //create button to add to viewer
        var previousButton = new OpenSeadragon.Button({
          tooltip: 'previous Image',
          srcRest: prefix + 'previous_rest.png',
          srcGroup: prefix + 'previous_grouphover.png',
          srcHover: prefix + 'previous_hover.png',
          srcDown: prefix + 'previous_pressed.png',
          onRelease: function() {
            console.log("foo");
          }
        });
        var nextButton = new OpenSeadragon.Button({
          tooltip: 'next Image',
          srcRest: prefix + 'next_rest.png',
          srcGroup: prefix + 'next_grouphover.png',
          srcHover: prefix + 'next_hover.png',
          srcDown: prefix + 'next_pressed.png',
          onRelease: function() {
            console.log("bar");
          }
        });

        scope.osd.addControl(previousButton.element, {
          anchor: OpenSeadragon.ControlAnchor.TOP_LEFT,
        });
        scope.osd.addControl(nextButton.element, {
          anchor: OpenSeadragon.ControlAnchor.TOP_LEFT
        });