If I had a couple of more points I would up-vote the second answer (passing in the jQuery 'event' argument).
I had unknowingly relied on the global event defined by browsers other than Firefox. I went back through my code and ensured I was always specifying the event parameter on all click events.
E.g.
$('#situationTextInput')
.val('')
.fadeTo(1000, 1.0)
.focus()
.off('keydown')
.on('keydown', function (event) {
VsUtils.handleSpanishTextKeydown(event);
});
I've also gotten into the habit of calling .off prior to .on as most of my code is using single pages, reusing content. Without the .off I was inadvertently stacking up events (even if they were the same callback) in subsequent steps of the dialog.
A side effect of changing my code to pass on 'event' directly to the handler was the binding to 'this.' changed. I chose to refactor the code to change 'this.' references to 'event.currentTarget.'