bug#7296: display-pixel-height not enough

[Eli Zaretskii]

> Date: Fri, 29 Oct 2010 12:13:49 +0200
> From: Jan Djärv <jan.h.d@swipnet.se>
> CC: Lennart Borgman <lennart.borgman@gmail.com>, 7296@debbugs.gnu.org
> 
> > What use-case could possibly want to know the dimensions that include
> > unusable portion?
> >
> 
> They are not unusable.  One can create a frame that covers the 
> taskbar/panel/whatever.

On MS-Windows?  If so, what is this bug report about?  It says:

  If you want to know how much height there is available to display a
  frame then display-pixel-height does not give you the information you
  need. The taskbar (w32 name, I have no idea what it is called on other
  platform) and other "bars" may have reserved some of the vertical
  space.

"Reserved" means, to me, that those parts cannot be used.  What am I
missing?