Nice. I like the in-place-with-overlay option particularly, though I can still interact with the other buttons while the overlay is in place which I was not expecting.
Usually these lightbox/modal overlays use an extra div either loaded with the page or injected on the fly that covers the entire window and is positioned just below the modal on the z-axis (z-index).
His solution was to give the button a really massive box-shadow :O
box-shadow: 0px 0px 0px 3000px rgba(0,0,0,0.8);
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| | <--- the box
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X <--- where Hakim thinksAnd at first I was impressed by the overlay, especially considering the novel implementation. However, after a little thought and setting that novelty aside, I think that effect is broken. It's simply not at all conventional for a fully masked page to retain interactivity (despite the odd site that allows this).
Worst case scenario, an unsuspecting user activates an overlay button, and while it's loading, starts clicking state-changing buttons around the page just to kill time.