What function is used when selecting a color in a Customize buffer?

Question

I don't like the function that Customize uses to select color. It spawns a new buffer that messes up window configuration, and is also difficult to search.

I want to replace this function with the following:

(defun helm-insert-color-hex ()
  "Insert the hex value at point for the color selected via helm"
  (interactive)
  (insert (apply 'color-rgb-to-hex (color-name-to-rgb (helm-colors)))))

How can I do this? I can't seem to find what that "Choose" button does (for example, when setting a foreground color for some face)

Answer 1

The function used to display the list of colors is list-colors-display. This function is actually called from the color widget, so that's the code you'll need to work with. Emacs widgets are documented in their own manual, available from Emacs via C-h i widget <ret>.