Issue: #2209
Fixes this error when signing with a HW wallet:
./electrum
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
python3: xcb_io.c:259: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
Aborted (core dumped)
The cause is likely with the `show_message()` calls. The proper fix
would be to hunt down where QT Gui elements are touched from a wrong
thread.
The workaround is to call XInitThreads(), as the error message suggests.