-enable the clipboard support
-support the GRAB/REQUEST/DATA/RELEASE verbs in both ways.
-pasting clipboard data is now "only-by-demand" from both sides (client and agent), whose behavior is symmetric.
-client and agent don't read or send the contents of the clipboard unnecessarily (e.g. copy, internal paste, repeating paste, focus change)
-bonus (no cost): support image cut & paste, currently only with win client
The configuration is received from Spice client.
The main usage of this option is for disabling display features in order to accelerate Spice performance over limited network connections.