Hello Dima,
My clipboard config is based on the default one - I just changed the verbose setting to "yes".
The log shows these messages the first time I try to paste: "This plugin does not support raise()" "This plugin does not support grabbing the keyboard"
This message is merely diagnostic, presumably from the Qt platform abstraction. I think it is not related to the clipboard.
Every next time, I get this message: "Error: invalid clipboard XML syntax"
If I set match_labels to "no", I don't get these messages and pasting works. What would be the proper clipboard config when match_labels is set to "yes"?
Can you please share your complete launcher, including the routing information?
I vaguely guess that you route the "clipboard" report to the global clipboard, not to the wm. As the application is a client of the wm, the label as observed by the nitpicker GUI server contains the "wm ->" as element. The clipboard's label matching can only work if the label of the "clipboard" report also contains the "wm ->" element. This can be achieved by routing the report session to the wm [1].
[1] https://genodians.org/nfeske/2019-07-03-copy-paste
Cheers Norman