Wow, my displaylink monitor works out of the box
This is a slithly older model and Bernie said they are not supported by Fedora...
It never worked in F17... so I was using the dock as merely USB port replicator. Installed F18 onto the 'bigtop' and there was an unkown monitor popping up.
The background is a little disorted, but other than that it works fine. I would say even better than DVI (it detects the external monitor left of the LVDS).
//edit: and my graphics card video memory is not freaking out any more if some monitor is connected to DVI (it's a radeon thing
[disi@localhost]~% cat /sys/kernel/debug/dri/0/radeon_pm_info
default engine clock: 680000 kHz
current engine clock: 99990 kHz
default memory clock: 900000 kHz
current memory clock: 150000 kHz
voltage: 900 mV
//edit: maybe, if I could put a solid colour as background somehow?
//edit: all black is fine
//edit: if I change to solid colour and then back to a normal image, it's fine.