ADDITIONAL INFO
---------------

I now started thunderbird using:

$ XDG_SESSION_TYPE=x11 WAYLAND_DISPLAY= thunderbird 


(I don't think those envvars do _exactly_ what I was looking for. For instance, I notice that ossobv/xpaste still doesn't get access to the send_event: https://github.com/ossobv/xpaste/blob/ea8b2ff9f839f9ecc345fd9d04014b99def5b112/xpaste#L182 )

It _does_ look like it changes things for the better because I haven't had it deadlock on me yet. And I've been moving mails for 45 minutes now.

The stdout/stderr definitely reports a change:


$ diff before after -U30
--- before	2022-06-06 13:23:30.137659175 +0200
+++ after	2022-06-06 13:23:13.921604292 +0200
@@ -1,40 +1,58 @@
-$ thunderbird 
+$ XDG_SESSION_TYPE=x11 WAYLAND_DISPLAY= thunderbird 
 [calBackendLoader] Using Thunderbird's libical backend
 [LDAPModuleLoader] Using LDAPDirectory.jsm
 [MsgSendModuleLoader] Using MessageSend.jsm
 [SmtpModuleLoader] Using SmtpService.jsm
+[GFX1-]: glxtest: Could not connect to wayland socket
 console.debug: "Trying to load /usr/lib/thunderbird/libotr.so"
 console.debug: "Trying to load libotr.so from system's standard library locations"
 console.debug: "Trying to load libotr.so.5 from system's standard library locations"
 console.debug: "Trying to load libotr.so from system's standard library locations"
 console.log: (new Error("Cannot load required OTR library", "resource:///modules/OTRLib.jsm", 109))
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
 console.debug: "Successfully loaded OpenPGP library librnp.so version 0.16+git20220124.f06439f7.MZLA from /usr/lib/thunderbird/librnp.so"
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
 console.debug: "Found 0 public keys and 0 secret keys (0 protected, 0 unprotected)"
 console.debug: "Successfully loaded optional OpenPGP library libgpgme.so.11 from system's standard library locations"
 console.debug: "gpgme version: 1.16.0-unknown"
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
 console.warn: services.settings: thunderbird/hijack-blocklists has signature disabled
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
-Unsupported modifier, resource creation failed.
-XXX: resource creation failed
+console.error: gloda.datastore: "got error in _asyncTrackerListener.handleError(): 19: constraint failed"
 IPDL protocol error: Handler returned error code!
 
 ###!!! [Parent][DispatchAsyncMessage] Error: PClientManager::Msg_ExpectFutureClientSource Processing error: message was deserialized, but the handler returned false (indicating failure)
 
 IPDL protocol error: Handler returned error code!
 
 ###!!! [Parent][DispatchAsyncMessage] Error: PClientManager::Msg_ForgetFutureClientSource Processing error: message was deserialized, but the handler returned false (indicating failure)



Hope this helps!

Cheers,
Walter