[LightDM] Configuring LightDM to not kill my session if VNC disconnects?

[Dawn Mew]

Hello!

I'm trying to set up a headless box that I can access via VNC, and then 
proceed to log into normally.

I put the following into my lightdm.conf:

[VNCServer]
enabled=true
command=/usr/bin/Xvnc -rfbauth /etc/vncpasswd
port=5900
width=1920
height=1080
depth=24

...And that works perfectly, except for one major problem: If I *ever* 
disconnect from the VNC, for any reason, my session and all running 
programs are immediately killed. Given the fragility of the internet 
(and yes, I'm tunneling over SSH, before anyone mentions VNC insecurity 
over the internet), I could be disconnected involuntarily at any time, 
not to mention the possibility of wanting to keep a program running 
indefinitely in a graphical session.

So, um... how can I configure my system so that my session is locked or 
suspended when VNC disconnects, instead of being completely destroyed 
like that? (And if I can't, could this be considered as a new feature? 
This is a networked remote-access protocol, the idea that it /must/ kill 
everything in the entire session on disconnect would seem to really 
reduce the feature's usefulness and robustness.)

Thank you!

--Dawn