about screen res and xorg

[Harry]

{Beware: Windbag alert}

I really am not up on how X is generated in modern linux distros,
and have come thru many years using the xorg.conf and back when it was
Xfree86 there was a similar conf file... I've forgotten the name.

For years I've been able to get a really massive desktop.  Way back
when, it was actually due to misconfig on my part but I got to liking
it. One thing I learned right away was that it kept other people off
my computer... most seem to find the big panning desktop really
disconcerting. I did too for the first few weeks but now I really like
it and feel awfully cramped on something like 1024x768

I've used lines like these in xorg.conf but in the new install of
ubuntu it appears to be ignored or overridden or whatever.

In:
 
,----
| Section "Screen" 
| 
|   [...]
| 
| 
|     Subsection "Display"
|         Depth       24
|         Modes       "1280x1024" #"1024x768" "800x600" "640x480"
|         Virtual     2048 1536
|         ViewPort    0 0
|     EndSubsection
|     
|   [...]
| 
| EndSection
`----

The `Virtual' line is what does the trick when it works.

Can anyone who understands the basic mechanisms in the modern approach
steer me toward getting the 2048x1536  Desktop.  I'm using the same
hardware where I was running Gentoo linux with that size desktop
configured. But the techniques in Ubuntu appear to be quite different
than what I was doing.

At any rate, I'm not at all clear on how to go ahead with it.