External screen, resolution and "small" desktop.

[Grunt]

Hi everyone!
I've installed LXDE on a eeePC 701 netbook, running Debian Sid.

When I login, LXDE starts with a 480x640 size, that fits for the 7" netbook screen.

I got a 19" CRT screen, that I use sometimes (not often) with my laptop.
When I plug it, I change the resolution to 1280x1024@75Hz and shut down the netbook screen, using the "Monitor Settings" tool.
(My screen seems to be buggy: if I leave to "Auto" the frequency, it rises up to 85Hz and the screen cann't handle that.)

It works well, but the desktop has a strange behavior: it keeps a 640x480 size.

Just imagine a wide grey background display of 1280x1024, and only the left up corner is the 640*480 desktop, with a few icons.

The lxpanel adapts itself perfectly and takes all the width of screen when I change the resolution.

I've googled and found this topic on the forum, and tried to add xrandr options to /etc/xdg/lxsession/LXDE/autostart.
But, with my screen, "1280x1024" gives an auto frequency of 85Hz, so it doesn't work. And if I go back to "1024x768" in xrandr option, this doesn't work and both screens keep on, with 640x480 resolution.

What would be perfect to me is a configuration that would:
- fix up this desktop issue,
- display only on the external screen, at 1280x1024@75, when the screen is connected,
- if it is not connected, keep the resolution to 640x480.

Thanks for your answers.

[archibald haddock]

I never liked software tools for display things. Always generating errors on any platform.
You could take a look at /etc/X11/xorg.conf configuration. You can add much more options to the xorg.canf then any GUI is providing on the run.
First you can look at /etc/X11/xorg.conf.example and lookup the options.