Shift-click to sample colors for a gradient

If you have a selected object filled with a gradient and you want to use the eyedropper to update the colors of the gradient, you can:

1. Click once on the gradient slider (house icon) you wish to modify
2. Activate the eyedropper (type i)
3. Shift click on the color you want to sample, updating the gradient slider.

Thanks to Ruxman