What resolution is displayed?

[reader at newsguy.com]

Sergio Monteiro Basto <sergio at sergiomb.no-ip.org> writes:

> I think you are looking for this 
> on menu -> system tools -> krandrtray
> or on kde control center, you have on peripherals display settings for
> your display.
>
> or simply by command line: krandrtray, attention that appears one icon
> on system tray of kde panel.

No, that too, only shows what size my desktop is set to.  Not the
actual displayed resolution.

Clicking on the tray icon shows:
[x] 2048 x 1536

And that is the size of my desktop as set in xorg.conf:
Note the `Virtual' setting.  However the displayed resolution is one
of the ones on `mode' line I think.  And can be walked thru with 
C-A +/-.

I want to see exactly what is being displayed out of those choices...


 [...]

 Section "Screen"
   Identifier "Screen0"
   Device     "Card0"
   Monitor    "Monitor0"
   DefaultDepth      24
   SubSection "Display"
      Viewport   0 0
      Virtual   2048 1536
      Depth     24
      Modes      "1400x1050" "1280x1024"  "1280x960" "1024x768" 
   EndSubSection