FXML expression binding

[Richard Bair]

> <CheckBox selected="${(boxA.selected &amp;&amp; boxB.selected) || boxC.selected}" />
> 
> note the &amp;&amp; instead of && for XML goodness.
> Also note that operator precedence is somewhat different from what you might be used:
> 
> ! boxD.selected && boxE.selected seems to be: !(boxD.selected && boxE.selected)

I'd probably call that one a bug. Whether it was or not!

> I conclude that FXML expression binding supports more than the most basic expressions but it is nowhere documented which ones exactly.
> I am curious what other expressions are supported.

At the time, I really wanted us to use UEL (same expression language used by JSF, JSP) for the following reasons:
    - EE engineers will be familiar with it
    - Lots of example code out there
    - Implementation already exists and is robust

There were a few things I felt needed fixing in UEL to be quite what I wanted, but basically I felt we should take it and go. Since then some other binding languages have come on the scene such as handlebars and I don't remember how many others we looked at. Should we just take UEL, or should we take a full survey of the JS state-of-the-art?

Richard