How to change Jupyter notebook busy indicator to something more visible

Jupyter_Busy_Indicator.txt

Most of this is just following the steps here:

http://sherifsoliman.com/2016/01/11/theming-ipython-jupyter-notebook/

On a recent Juypter version, open up the custom.css in your favorite editor which should be Sublime Text 3 or Vim and definitely not emacs.

~/.jupyter/custom/custom.css (on my VM this lives in C:\Users\username\.ipython\profile_default\static\custom -- YMMV)

Do a search for kernel_busy_icon

That busy/idle indicator circle thingy is actually just a font from Font Awesome.
http://fontawesome.io/icons/

That makes this happily very easy. 
Just find one you like, and feel free to change the icon and font size for it.

Here's what I ended up using. A Big Red media "play" thingy in a circle:


.kernel_busy_icon:before {
  display: inline-block;
  font: normal normal normal 14px/1 FontAwesome;
  font-size: 28px;
  text-rendering: auto;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  content: "\f01d";
  color: #d9534f;
}