function navHandler() {
     switch(window.event.keyCode) {
         /* Go to next picture */
         case 32:        // Space
         case 39:        // Right arrow
             navNext.click();
             break;
         /* Go to previous picture */
         case 37:        // Left arrow
             navPrevious.click();
             break;
         /* Go up to index */
         case 36:        // Home
         case 27:        // Escape
             navIndex.click();
             break;
         /* Ignore the key otherwise */
         default:
     }
 }