[O] emacs.SE question re: org-agenda

[Loyall, David]

Hello.

Here is a conversation from the emacs Stack Exchange question and answer 
website.  It's from December.

Asker> I would like to make it easy to find where are the free
Asker> blocks of time in my org-mode agenda.
Asker> 
Asker> For instance, if I have two appointments one
Asker> 9:30am-10:30am and another 11:15am-12:30pm, I would like
Asker> to see at a glance that the 10:30am-11:15am block is
Asker> free.
Asker> 
Asker> In other words, I want to be able to distinguish free
Asker> time as easily as it is done in a graphical agenda such
Asker> as Google calendar.
Asker> 
Asker> Is there a way to make the empty blocks of time easy to
Asker> see? Perhaps to colorize the empty blocks that are
Asker> longer than a given number of minutes?

Commenter> Is the org-agenda-time-grid not sufficient for your
Commenter> needs?
Commenter> 
https://www.gnu.org/software/emacs/manual/html_node/org/Time_002dof_002dday-specifications.html

Asker> The grid is not enough, as it shows ups even when the
Asker> time is busy (e.g., if there's a 9:30am-10:30am meeting,
Asker> there will be a grid line at 10:00am). I would like busy
Asker> and non-busy times to be easy to distinguish.

Asker> I have thought a little bit more about this
Asker> functionality. I believe the most useful and simplest to
Asker> implement would be to change the color of the time block
Asker> (only the name of the time block, e.g., 8:00-9:00) for
Asker> those time blocks that have more than a given amount of
Asker> free time (e.g., more than 15 minutes). Both the color
Asker> and the minimum free time should be user configurable.

(from 
http://emacs.stackexchange.com/questions/5395/show-free-blocks-of-time-in-org-modes-agenda)

A brief search of the most recent ~32k mailing list posts didn't tell me how to 
answer this question.

Does anyone here know?

Cheers,
--Dave