code: function (o) {
              // The input argument is either an Event or a TapRecognizer. Both have the same properties for determining
              // the mouse or tap location.
              var x = o.clientX,
                  y = o.clientY;
  
              var redrawRequired = highlightedItems.length > 0; // must redraw if we de-highlight previously picked items
  
              // De-highlight any previously highlighted placemarks.
              for (var h = 0; h < highlightedItems.length; h++) {
                  highlightedItems[h].highlighted = false;
              }
              highlightedItems = [];
  
              // Perform the pick. Must first convert from window coordinates to canvas coordinates, which are
              // relative to the upper left corner of the canvas rather than the upper left corner of the page.
              var pickList = wwd.pick(wwd.canvasCoordinates(x, y));
              //console.log(wwd.frameStatistics.frameTime);
              if (pickList.objects.length > 0) {
                  redrawRequired = true;
              }
  
              // Highlight the items picked by simply setting their highlight flag to true.
              if (pickList.objects.length > 0) {
                  for (var p = 0; p < pickList.objects.length; p++) {
                      pickList.objects[p].userObject.highlighted = true;
  
                      // Keep track of highlighted items in order to de-highlight them later.
                      highlightedItems.push(pickList.objects[p].userObject);
                  }
              }
  
              // Update the window if we changed anything.
              if (redrawRequired) {
                  wwd.redraw(); // redraw to make the highlighting changes take effect on the screen
              }
          }
docs: The pick-handling callback function.