Why can't I see the Customer Filter icon?!

Kibana 4.2.0 with ES 2.0 and LS 2.0 and Shield2.0

I have setup a +filter and would like to customize the filter criteria in it. The documentation talks about a custom filter but when I hover over that filter definition I do not see that pencil icon or ability to customize filter in my kibana instance.

I'm Logged in as es_admin (created according to Shield instructions for es_admin). Same thing in an unsecured version of KB4.2 on another box.

Current in the docs means 4.3, you will need to upgrade.

I have upgraded to K4.3 and ES2.1 - I can get icon now.

I want to modify the Filter - can I write an expression for a Range of Values in a given field?

I have tried this, but I get a syntax error:

I'd appreciate some guidance on this - would solve an important problem for my client.

That's not valid JSON... are you trying to detect if the time difference between orderDeskTimestamp vs orderArrivalTimestamp is >= 1 and <= 12 using Groovy?

Yes, I'm trying to setup a filter where the difference in days between the two dates is within a specified range: between 1 and 12 days (it's the SLA). How can I achieve that here?

I'll be honest, I don't know what this script is here: JS, JSON or GROOVY.... I'm lost.