code: function showJumpBox(){
  
      // If the box is already visible, do nothing
      if(jumpBoxShown) return;
      jumpBoxShown = true;
  
      // Create the containing element
      var f = document.createElement('div');
      f.id = "jumpto";
  
      // Construct some basic HTML
      f.innerHTML = [
        '<div class="overlay"></div>',
        '<div class="box">',
          '<form id="jumpform">',
            '<input id="jumpbox" type="text" name="line" placeholder="Go to line..." autocomplete="off" />',
          '</form>',
        '</div>'
      ].join('');
  
      // Add the keydown event
      addEvent(f, 'keydown', jumpFormKeyDown);
  
      // Add the container straight onto the body
      document.body.appendChild(f);
  
      // Focus the field, and bund the submit event
      document.getElementById('jumpbox').focus();
      addEvent(document.getElementById('jumpform'), 'submit', jumpFormSubmitted);
    }
docs: ## showJumpBox
  
  Constructs and shows the jump box