Gradient Picker: create a complex gradient in one drag

Migrated from https://bugs.launchpad.net/inkscape/+bug/170630
From 2005-03-16

Summary:

I use Inkscape every day to create logos and I start from a bitmap really often.

There is a tool which can make me save a lot of time is a "gradient color picker":
Instead of clicking on one pixel to get its color, it would be simple and powerful to trace a line from one point to another and set the number of controls (from 2 to n) to put in the gradient.