Cursor not visible in GtkTextView

[Richard Shann <richard shann virgin net>]

I have a GtkTextView widget which refuses to display the cursor. All the
other editing commands seem fine (marking text, switching to overwrite
mode and back) but despite calls to gtk_text_view_get_cursor_visible()
reporting TRUE, no cursor is visible.
This text view widget is packed in a scrolled window in a GtkVbox in a
GtkFrame in a GtkNotebook in a GtkWindow. If, instead I put it directly
in a top level window the cursor shows.
The Gtk version 2.20.1, does anyone have any insights into this problem?

Richard Shann