How does the eye-dropper color picker work for fusion titles

I was grabbing the eye-dropper to pick a custom color for a Fusion title and it just doesn't seem to work. I can double-click the color swatch and select the 'Pick Screen Color' option but I was expecting to be able to grab the eye-dropper and just drag it over my video image and release to accomplish the same thing.
Is this a bug (incomplete feature) or am I supposed to be combining this action with a keyboard key, etc,?
Thx
Is this a bug (incomplete feature) or am I supposed to be combining this action with a keyboard key, etc,?
Thx