code: function(elem, f) {
     // console.log("in onAppend, elem: "+elem);
    var observer = new MutationObserver(function(mutations, me) {
        //console.log("in mutationObserver, me: "+me);
        mutations.forEach(function(m) {
          console.log(m);
          if (m.addedNodes.length) {
              f(m.target, m.addedNodes)
          }
      })
    })
    observer.observe(elem, {childList: true})
  }
docs: /*  //trying to figure out global styles that customize gui items
  var styles = StyleSheet.create({
  fontFamily: {
  type: 'string',
  default: 'Helvetica'
  },
  fontColor: {
  type: 'string',
  default: key_offwhite
  },
  borderColor: {
  type: 'string',
  default: key_offwhite
  },
  backgroundColor: {
  type: 'string',
  default: key_grey
  },
  hoverColor: {
  type: 'string',
  default: key_grey_dark
  },
  activeColor: {
  type: 'string',
  default: key_orange
  },
  handleColor: {
  type: 'string',
  default: key_offwhite
  },
  });