QWERTY

Another late night working. I'm refining a presentation I am giving tomorrow. I've got so much I want to say but only have 15 minutes in which to say it. I just rehearsed it. At warp speed I managed to fit it into 16 minutes. That means I need to edit quite a bit. But what to leave out! Meantime, looking at the image of my keyboard I realise that it needs a clean! Where does the dust come from and why did it only show up when I snapped it?