Homepage: https://www.gnu.org/software/emacs
Author: Miles Bader
Only show defaults in prompts when applicable
Defines the mode `minibuffer-electric-default-mode'. When active, minibuffer prompts that show a default value only show the default when it's applicable -- that is, when hitting RET would yield the default value. If the user modifies the input such that hitting RET would enter a non-default value, the prompt is modified to remove the default indication (which is restored if the input is ever restore to the match the initial input).