code: function(margins) {
          $.console.assert($.type(margins) === 'object', '[Viewport.setMargins] margins must be an object');
  
          this._margins = $.extend({
              left: 0,
              top: 0,
              right: 0,
              bottom: 0
          }, margins);
  
          this._updateContainerInnerSize();
          if (this.viewer) {
              this.viewer.forceRedraw();
          }
      }
docs: The margins push the "home" region in from the sides by the specified amounts.
  @function
  @param {Object} margins - Properties (Numbers, in screen coordinates): left, top, right, bottom.