I have code that works in my GTK2 version. When the crash occurs the TextBuffer is in an as-created state. I attempt to serialize it for use as the last resort in my undo stack:

   ubyte[] serialize()
   {
      TextIter start = new TextIter();
      TextIter end = new TextIter();
      tb.getBounds(start, end);
      GdkAtom atom = tb.registerSerializeTagset(null);
      ubyte[] buffer = tb.serialize(tb, atom, start, end);
      return buffer;
   }

Any thoughts?