Yes. That is what I discovered. Having finally realised that I was working with kdm and not gdm, (it's confusing having both installed), the problem was simply solved. The repository's LXDE packages installed by Gslapt give you a LXDE.desktop file in: /usr/share/xsessions
You have to move or copy this file to: /usr/share/apps/kdm/sessions/LXDE.desktop
If you don't find one you can create one modelled on /usr/share/apps/kdm/sessions/icewm.desktop, leaving out all the unnecessary locale comments. (I wonder how much hard drive space we'd save if we stripped all the un-needed locale customisation from Linux files? When I stripped the ICEWM.desktop file of un-needed code the size went down from 4.8kb to 149bytes) Logout and then login again, and you can start LXDE by selecting it from the Sessions menu, and not by using the console.
If you are working with gdm as your login manager, then you need to create an executable file /etc/X11/xinit/xinitrc.lxde I found that this was not provided by the installation of the LXDE packages with gslapt. The xinitrc.lxde file can be modelled on an example file in the same directory - "xinitrc_example", or you can use GrannyGeek's file posted earlier in this thread. If you use the example file, save it in the same directory as: xinitrc.lxde and remember to make it executable after saving it - code:
chmod +x /etc/X11/xinit/xinitrc.lxde
This file and the others like them in this folder (xinitrc.icewm, xinitrc.jwm, etc. ) can now be picked up by a sub-routine in the shell script: /etc/X11/gdm/Xsession and the desktop or window managers should display in the Session menu of your login screen.
I am pleased to have LXDE up and running on VectorLinux Light. It is worth having. I don't think it is any more resource hungry than IceWM and it is easier to customise. I will mark this thread as solved, but before I do, can anyone help with one niggling problem that remains with this installation of LXDE? The menu has a logout button. Clicking it just gives you the option to logout. You don't get a menu of options - Reboot, Shutdown, etc. as you do with IceWM. You have to logout to the login screen and reboot or shutdown from there. Surely this wasn't intended?
Can this be changed so that you can reboot or shutdown in one operation?