Gmail Page Turning Pixels?

If you haven't noticed it already, something is lurking behing your Gmai page.

Just watch closely what's on the top left corner... do you see it?

Yes... a very small "fold" which was introduced recently and just sits there unexplained.

As usual, a lot of conspiracy theories are popping up...

Under close inspection, that element turns out to be curious IFRAME, which shouldn't really be needed - or could at least be completely invisible.

Is this a way to prepare us for whatever's beneath Google Gmail service?