Clipboard bugs

[iDmple]

Issue to track the server-side of Xpra-org/xpra-html5#326

• when "clipboard direction is set to-server, Xpra-html5 internal copy paste does not work anymore" - which would be an xpra bug
• the server sends clipboard data even when to-server is set - I believe this only happens for "greedy" clients (like MS Windows, MacOS and html5) - another xpra server bug
• "when clipboard is enabled and clipboard direction is set to-server, Xpra-html5 internal copy paste does not work anymore" - another xpra server bug?

I'm running Xpra version 6.2.0-1 (.deb package) on Ubuntu 24.04 (k8s) and Xpra-html5 16.2 on Mac with Chrome Version 130.0.6723.59 (Official Build) (arm64).