How to spawn a thread within a GtkD button event handler

[Alaindevos]

I created blindly a thread and this allowed to do stuff in 
background.
But when i passed the mainwindow as argument and did some stuff 
it resulted in,
[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.
Assertion failed: (!xcb_xlib_threads_sequence_lost), function 
poll_for_event, file xcb_io.c, line 263.
Program exited with code -6