Following is from Buster, but it's the same on Bullseye: # /usr/local/smnxt/seamonkey -P smnxt & (seamonkey:1347): Gtk-ERROR **: 15:41:01.711: GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported ExceptionHandler::GenerateDump cloned child 1353 ExceptionHandler::SendContinueSignalToChild sent continue signal to child ExceptionHandler::WaitForContinueSignal waiting for continue signal...
(crashreporter:1358): Gtk-ERROR **: 15:41:01.774: GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported
[1]+ Trace/breakpoint trap /usr/local/smnxt/seamonkey -P smnxtmoz
# dd /usr/local/smnxt/seamonkey /opt/trinity/lib/kgtk/libkgtk2.so (0x00007f477ddfa000)
# cat .xsession-errors Xsession: X session started for root at Sun 13 Jun 2021 05:10:39 PM EDT dbus-update-activation-environment: setting DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/0/bus dbus-update-activation-environment: setting DISPLAY=:0 localuser:root being added to access control list [tdebuildsycoca] tdebuildsycoca running... XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":0" after 275 requests (275 known processed) with 0 events remaining. [2021/06/13 17:19:28.132] kded: Fatal IO error: client killed [2021/06/13 17:19:28.132] [tdeinit] Fatal IO error: client killed [tdelauncher] Exiting on signal 15 XIO: fatal IO error 2 (No such file or directory) on X server ":0" after 185 requests (185 known processed) with 0 events remaining.
No such problem running IceWM instead of TDE.