[Grace-core] Backstop

[Prof. Andrew P. Black]

> On 7 Jun 2016, at 21:58 , Timothy Jones <tim at ecs.vuw.ac.nz> wrote:
> 
> 
> On 08/06, Andrew P. Black <black at cs.pdx.edu> wrote:
>> It stops the backspace key from making Chrome go “back” to the
>> previous web page, which is really annoying when you think you are
>> editing a Grace program in the browser-based editor.
> 
> You can also implement this directly on the page with something like:
> 
> document.addEventListener("keydown", function (event) {
>  if (event.which === 8) {
>    event.preventDefault();
>  }
> });

Good to know.  We should just do this — as should _every_ web page with a  fillable form!

Incidentally, what is the _right_ way to get hold of the grace-web-editor session from within the JavaScript that is running on the web page?

	Andrew