GtkTextBuffer and the insert-text signal

[Michael Terry <mterry fastmail fm>]

Hello.  I am porting an application from GTK+ 1 to GTK+ 2.  Of course, 
one of the big issues is changing from GtkText to GtkTextView. 
Unfortunately, I am having a problem with the "insert-text" signal.  In 
particular, it seems that some of the parameters to my callback function 
are getting garbled along the way.

I register the callback using g_signal_connect (or 
g_signal_connect_after -- both give same results) with the following 
prototype:

void function (GtkTextBuffer *Buffer, GtkTextIter start, gchar *text, 
gint size, gpointer data);

When it gets called, the GtkTextBuffer pointer is fine, as is the user 
data.  Unfortunately, the string, length, and iter are all garbage.  I 
can't determine why this is happening.  No other callbacks are 
registered that alter the GtkTextBuffer in any way (that I can find).

What are the possible reasons the parameters could be awry?  Am I 
changing the text before the callback is called?  Am I using some API 
call wrong?

This is with GTK+ 2.2.1.

Thanks for any help.

-Mike