How to spawn a thread within a GtkD button event handler

[Alaindevos]

One thing I want to do is in an eventhandler of a button released 
event which takes minutes in duration to change the state of the 
statusbar indicating something is going on.
But the statusbar is not redrawn before the evenhandler finishes.

Better would be to start a new thread but D-spwawn-threads can 
not call member functions of the MainWindow calls so some 
plumbing with gtk is needed. This thread would coexist with the 
gtk main eventloop. The GTK docs on this look overwhelmingly 
complicated at first.