Blur document.activeElement on $.modal('show')

You don't really want to be able to type things into an input which is obscurred by a modal window, so focus should probably be blurred when modal is shown.

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It might make sense to 'remember' the selected elements and re-focus them on $.modal('hide'), I dunno. I think doing that could pose some potential problems.

I do realize that other frameworks leave this up to the developer to do during the show/hide events -- and that is certainly one solution. However I feel like it's not really a good UX to NOT do this, so it's kind of silly to require a developer to register an event handler for it. Further, it is awkward for MVVM frameworks, because the events emitted by the modal element will most likely end up dealing with a controller, who should not be messing with the DOM at all. Ergo, it seems a simple thing to make this a configurable behaviour, but it probably makes the most sense to just do it all the time.