Multiple Desktop Sessions on Mac OS X Tiger

Multiple Desktop Sessions allow more than one person to use your Macintosh computer at the same time! In Panther (Mac OS 10.3), Apple introduced "Fast User Switching" which allowed additional users to log on to the mac without the original user logging out. Instead, the original user's desktop was carefully tucked away and could be switched back to when needed. Now in Tiger (Mac OS 10.4) all those desktops can be accessed simultaneously using Vine Server (OSXvnc). This allows multiple users to be logged in, each using his or her own desktop on the same Mac. For example:

While my daughter plays her computer game on the monitor attached to the computer...
While I access my files through the Finder and develop with XCode...
While my son can launch iTunes and have it stream music over AirTunes...
My wife can read emails and check weather on her Dashboard.
All at the same time!

All they need is a computer or PDA running a VNC viewer to access Vine Server (OSXvnc). Now you have a use for all those old PC's!

How do I set it up?

First download Vine Server (OSXvnc) on your computer. Vine Server (OSXvnc) is freely available in our download area.
Once downloaded, just move the Vine Server (OSXvnc) application into your Applications folder to install it.
You'll need to enable Fast User Switching if you haven't already done so. It can be found under System Preferences -> Accounts. Choose "Login Options" near the bottom and check the box to "Enable Fast User Switching".
The following process should be repeated for EACH USER that wants access to the machine through VNC:
- Log in via Fast User Switching (if not already logged in).
- Launch Vine Server (OSXvnc) from inside the Applications folder.
- You should see the message "Server Running" near the bottom of the configuration panel. If you get a message stating "Port In Use" try setting a different Display Number and hitting the "Start Server" button. Each user must be running on a different port.
- Now Ctrl-Click on Vine Server (OSXvnc) in the dock and choose "Open At Login"; this will set it to launch whenever this user logs in.
- Launch a VNC viewer on another machine and enter the connection information for the machine that you just configured. If you are using Chicken of The VNC you should see each screen via Bonjour. Otherwise, each user has an associated Display Number which corresponds to the port number 5900.

Notes and Caveats

Each user MUST be logged in using Fast User Switching. If you reboot the computer you will need to go and log-in each user with Fast User Switching to enable access via VNC.
It's still a single machine. If lots of people are doing lots of things at once you will notice a slowdown.
This doesn't duplicate your hardware. Two people can't try to play music out the speakers at the same time, you can't have different people each copying files from the same USB camera, things like that.
We have seen inconsistencies when different users try changing the desktop size/color depth. Sometimes this will have an impact on other users or cause things to behave strangely.
Trying to Fast User Swtich from a user who is already "off-screen" will be ignored.
There is currently a bug in Apple's keyboarding routines which causes some keyboard states to persist across sessions. If the user at the Mac's keyboard is holding down a modifier key (like Command) when you hit another key (like A), you will get their modifier in addition to your key.
If you have difficulties getting the server to run (or stay running) we recommend verifying these settings in Vine Server (OSXvnc):