How do I validate the input to a gtk.Entry on gtkD?

[Busiki]

I want to put in the field gtk.Entry converted characters.

Here it tells how to do it on the GTK:
http://developer.gnome.org/gtk-faq/stable/x842.html

But in gtkD not realized the function 
g_signal_handlers_block_by_func(),
and I need to stop at the time of recording in the Entry field 
effect signal addOnInsertText().

If it is not locked, then begins an infinite recursion call this 
signal.
What are the opportunities to stop the operation signal and then 
unlock.