Make color picker work outside of blender's screen

Currently, if you try to pick a color using the color picker, you can only pick from things that are in Blender's window.

In Substance Painter, you can click the color picker, and then drag it to anywhere - open references images, a google search - anything that's on your computer, it can sample. This would be MUCH faster than importing the image or getting the hex code etc, since we already have the images on our computer.

So tl;dr: let color picker get the color of anywhere the mouse is dragged over, even if it's out of blender's window.