how to disable the F12 widget screen thing?

When you hit F12, and some other keyboard combos, your desktop disappears and you get a blank desktop with a weather widget and a calculator. I don't know what this screen is called, so ill call it the widget screen here.

I touch type > 40wpm, but frequently I accidentally hit F12 instead of backspace, which kills my work dead in its tracks. Sometimes I don't realise as I am typing as I reading it from a book. Then I have to figure out how to get rid of this screen, then fix what I was doing. Its incredibly annoying.

How do I permanently get rid of this widget screen? I never want to see it again. If I want a calculator, ill open the calculator on my desktop.