I created a <<textboxPlus>> widget which should make doing what you want a lot easier.
Once you add that widget, all you’d need in the passage is:
<<textboxPlus "Label: " "$varName" `{ autocomplete: "off" }`>>
See that link for all of the other options it has.
Hope that helps! 
P.S. If it doesn’t show up, then you may need to hit CTRL+F5 to refresh the page in your cache.