[K12OSN] default configuration questions

[Jon Harder]

I have three configuration issues that I have not been able to
resolve.

First, how can I set the preferred mailreader to default to thunderbird?
That is, when a user first logs on, it is already thunderbird and they
do not need to select it via the System -> Preferences -> More Preferences ->
Prefered Applications menu.

My second question involves selecting a default login screen for the client
computers. My current configuration includes this in
/opt/ltsp/i386/etc/lts.conf:

        SCREEN_01          = startx
        SCREEN_02          = rdesktop
                RDP_SERVER = tserve
                RDP_OPTIONS = -a 16 -f
        SCREEN_03          = shell

Clients randomly choose between SCREEN_01 and SCREEN_02 when they
start up. I want it to open consistently on SCREEN_01. Hopefully most
users won't even need to know about rdesktop. I tried delaying the startup
of SCREEN_02 with a sleep of several seconds, but no luck with that.

Finally, how do I change the default image on the linux login screen.
Does it need to be a certain size?

Thanks,

--
Jon Harder
Mountain Lake (MN) Public Schools