Add a colour picker as a background option

For an item background, sometimes a simple colour (or if you're feeling adventurous, even a 2-colour gradient) is all you need. I'm struggling to find a simple way to generate a single colour image.

It would be even better if you did not have to create a media item to have such a background. It should be a tab so you set a background to a solid or gradient colour.

Where ever you can change the colour, there should be a colour picker that can pick any colour that is on my screen, even outside presenter.