Hi,
It will work if the Messages App has either AIM (or AIM Valid) names or Jabber valid IDs listed as accounts.
(i.e the iChat side of things)
I have Screen Shared to Snow Leopard and Leopard computers.
My G4 tower will boot into an iChat 3 version.
This will only accept Video Chats if the iChat 3 end calls ( I have yet to try Screen Sharing with iChat 3).
I actually don't have a computer that I can booth into Lion whilst being in Mountain Lion.
Lets say you are using an iCloud issued @me.com name as the iMessages Apple ID
Go to the Message Preferences > Accounts and us e the + button
Click the AIM Choice.
Add the @Me.com name in full
Click Done.
You will now have an AIM Account in the Accounts list
In the window Menu it will now says Buddies (CMD + 1)
This will show you the Buddy List
Add AIM or AIM Valid Buddy names.
In the Video Menu Screen Sharing will now be an option you can tick (or Untick)
You could also Add GoogleTalk or other Jabber IDs to the Accounts list. (GoogleTalk is a Jabber server)
Screen Sharing is AIM to AIM or Jabber to Jabber.
10:26 PM Thursday; October 4, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.2)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously