RE: x-display-pixel-width/height inconsistency

[Drew Adams]

> > I think `fit-frame-to-screen' would be a nice command for 
> > emacs to have.
> 
> +1

Not sure whether this is exactly what you have in mind (it does nothing special
wrt multiple displays).  But FWIW, command `maximize-frame' in `frame-cmds.el'
does that.  It also lets users reserve part of the display for the MS Windows
task bar or for the Mac "smart tool bar" (or whatever).

,----
| maximize-frame is an interactive compiled Lisp function in `frame-cmds'.
| (maximize-frame &optional DIRECTION FRAME)
| 
| Maximize selected frame horizontally, vertically, or both.
| With no prefix arg, maximize both directions.
| With a non-negative prefix arg, maximize vertically.
| With a negative prefix arg, maximize horizontally.
| 
| In Lisp code:
|  DIRECTION is the direction: `horizontal', `vertical', or `both'.
|  FRAME is the frame to maximize.
`----

Command `restore-frame' returns a frame to its pre-maximized size and position.
Command `toggle-max-frame' does both, alternating: maximize/restore.

code: http://www.emacswiki.org/emacs-en/download/frame-cmds.el

description: http://emacswiki.org/emacs/FullScreen#frame-cmds.el