I have used createTemplateFromFile many time in the past. It lets me use an include method so that CSS and JavaScript can be broken out into a different file. But today I can't seem to make it work. Below is my test code bound to a spreadsheet. Any ideas why its not working? I tried another existing spreadsheet with a custom dialog using the technique and it works.
Code.gs
function onOpen() {
var ui = SpreadsheetApp.getUi();
var menu = ui.createMenu("Test"); …