Thanks for reply. I had already - "Maybe you can search google" with no luck.
(the Monitor is a DGM, L-1523, 15.4") but your prompt made me realise that I had not searched for
+"xorg.conf" +"1280x720" and that did produce several results.

You are right about the Horiz & Vert numbers, and DisplaySize does make a significant difference - to the text size - but no effect on enabling a higher resolution mode. 
After getting 1280x720 to work I can see why - more further on.

So I added a Modes Section and used a selected google result for the numbers.

It then worked.
 
But, now that I have seen 1280x720 running I am not that taken by it.
Circles are ellipsoidal with the major axis running top to bottom, and I have to play with the fonts to get back to a display that I like.  This in turn affects the log-in screen (I want to use the Gnome with Browser login.)

On thinking about the display it is easy (now) to see why Xorg has some difficulty with it. 
The DisplaySize is 331mm x 208mm and the pixel pitch is 0.2588mm H&V.

So 1280x0.2588 = 331.26400mm (fine that fits)
and 720x0.2588 = 186.33600mm  (hmmm, what about the other 21.664mm's worth of pixels, at least 83 of em?)
The display also supports 1024x768 and 768x0.2588 = 190.7548mm so the display is not so distorted in the top to bottom mode at this resolution.

I originally thought that the aspect ratio would be 16/9 as it was advertised as a "Wide Screen" and 1280x720, both having the ratio 1.777... I just did not note that the viewing area ratio was actually 1.5913.

Anyway, thanks to your posts I can use 1280x720 if required.
 
I'll run some video on it and do some testing then post some results on this forum.
I suspect it might be a popular LCD as it's cheap and works quite well. 

I'm wondering how one could use 1024x768 for general purpose use then change the resolution automatically just before running a photo or video program.
Bit of research & scripting required here.

Again - Thanks a lot Nick.

Z

[code=Monitor section]
    HorizSync    30.0 - 62.0
    VertRefresh    56.0 - 75.0

#    DisplaySize    <width mm> <height mm> # This could help xorg a bit
[/code]

[code=Screen Section]
    DefaultDepth    24

    Subsection "Display"
        Depth    8
        Modes    "1280x720" "1024x768" "800x600" "640x480"
    EndSubsection
    Subsection "Display"
        Depth    16
        Modes    "1280x720" "1024x768" "800x600" "640x480"
    EndSubsection
    Subsection "Display"
        Depth    24
        Modes    "1280x720" "1024x768" "800x600" "640x480"
    EndSubsection
[/code]

Then it's recommended to install the nvidia driver (better performance) and configure your xorg.conf device section like so:
[code=Device Section]
    Driver        "nvidia"

    Option        "NoLogo"        "true"
    Option        "RenderAccel"        "true"
    Option        "AllowGLXWithComposite"    "true" # If you want the compositor working
#    Option        "UseEdidFreqs"        "false" # Uncomment to ignore nvidia's edid
[/code]

And to make the nvidia driver happy:
[code=Module Section]
    Load        "glx"
[/code]

Hopefully this will bring you a bit closer too your final xorg.conf config . I you have more problems, please attach a link with you xorg.conf.
And about xorg not supporting your resolution: AFAIK xorg can run on every resolution, so that should be a big problem.

Regards driver - have not yet installed the full nvidia driver.

Driver entry in xorg.conf is "nv"

? where, how.  Monitor is "DDC1/DDC2B Compliant" only according to manual.

Good news is;-  the Section "Extensions" cleared up the error msg's.

When changing the Screen modes (from 1280x1024) to 1280x720 in xorg.conf
this only enabled a number of lower resolution screens.

So I increased Monitor "VertRefresh" to 43-75 - (hmm, I assume this defaults to Hz?)
anyway after this the text size became larger, still no 1280x720 mode, but can set 1024x768.

This LCD does 262k colours ? (True Color according to manual (Chinese)) 
where does this number come from !

Next I changed the Screen DefaultDepth  from  24 to 16, as I'm suspicious about 262k colours.

This further enlarged text size!  In fact I think it's back to where it was before I started on the
sub-pixel hinting check box.  But still no 1280x720 display mode available.

I'm not sure how to set DefaultDepth - I haven't found a way to relate the display manual value
of 262k colors to default depth, but 16 seems to work well so I'll stick with it.

Xorg.0.log   tells me card is supported.   X window Ver. 7.0.0
Also it thinks a CRT is connected not a flat panel.  Perhaps the LCD does not communicate
in a standard way.
Looked in the xorg.conf(5x) man pg., added DisplaySize entry.  This too enlarged text.
But still no 1280x720

Will X window Ver. 7.0.0 support WXGA 1280x720 ?

----------------------------------------------------------------------------
In LCD Manual;-
                     Incoming Display Mode
            Horiz Freq        Vert Freq
Resolution - 1280x720        63.981          60.020

Input signals: RGB analog,  FH: 30~62 kHz.   FV: 56~75 Hz   
-----------------------------------------------------------------------------

Any of this trigger some more ideas ? 

Thanks again.

Z

When first installed (clean install) the Xfce panel text is a nicely proportioned size, as is the panel drop down menus.

After checking sub-pixel hinting, in the User Interface Prefs, the panel text size and the drop down menu text size
then becomes very small.   It does not return to it's previous size when unchecked ?

These font size of the panel is the same as all other gtk applications, maybe you
have some problems with the nvidia driver (if you have one), if so maybe disable
EDID works. Anyway it's not panel related.

No it shouldn't.

Add 1280x720 mode in the screen section of xorg.conf and remove the bigger sizes.

Add:
Section "Extensions"
    Option        "Composite"        "Enable"
EndSection

to xorg.conf

It's a bug in xfdesktop that will be fixed soon (maybe it already is in svn)

After checking sub-pixel hinting, in the User Interface Prefs, the panel text size and the drop down menu text size
then becomes very small.   It does not return to it's previous size when unchecked ?

Should enabling sub-pixel hinting change the text size ?
Selecting LCD panel in Ubuntu Gnome does not change font size.

Any Xfce wizard able to point me in a suitable direction to set panel text size?

Other info.
Display is cheap DGM LCD running 1024x768 (but could do 1280x720 (WXGA) if I can get X11 configured properly)

xsession-errors
xfwm4 warning - disp. does not support  XComposite extension
xfwm4 warning - Compositing Mgr. disabled
xfdesktop gtk - CRITICAL - gtk_style_finalize:  assertion 'style->attach_count == 0'  failed 

Thanks.