Make sure updatemenus work when options are changed

[rreusser]

Sliders failed a bunch when @bpostlethwaite manipulated the options because the input events were using closure data that had been created before manual internal manipulation of slider steps had occurred. The simple fix is to fe-fetch the steps/buttons inside user input callbacks. #1233 fixed this for sliders. Need to:

• investigate whether it's a problem for updatemenus
• fix it if so
• apply a nice addition like Re-look-up slider position when the options change #1234 to make it even better

[gvwilson]

Hi - this issue has been sitting for a while, so as part of our effort to tidy up our public repositories I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our stack. Cheers - @gvwilson