Threading to prevent GUI Freeze

[TheDGuy via Digitalmars-d-learn]

> I wrote a demo for GtkD showing how multi-threading and D work 
> together, it's in the demos/gtkD/DemoMultithread folder of 
> GtkD, hopefully it will be helpful. However this example it is 
> based on using the GTk threadIdle callback which is generally 
> preferred over the locking methods you show above, obviously 
> though your use case may vary but keep in mind the locking 
> methods have been deprecated, see the GTK 3 reference manual 
> here:
>
> https://developer.gnome.org/gdk3/stable/gdk3-Threads.html
>
> You also see this GtkD issue here for 
> https://github.com/gtkd-developers/GtkD/issues/137 for some 
> code on how to use Delgates with gdk_threads_add_idle (i.e. 
> GtkD gdk.Threads.threadsAddIdle).

Thanks for your example code. Do i need those extern (C) 
function? Why is it not possible to write the value to the 
TreeView in D?