And a setter.

What is the use case?

A key binding that acts not entirely unlike this:

static gboolean
gtk_cell_editable_key_press_event (GtkEntry    *entry,
				   GdkEventKey *key_event,
				   gpointer     data)
{
  if (key_event->keyval == GDK_KEY_Escape)
    {
      entry->editing_canceled = TRUE;
      gtk_cell_editable_editing_done (GTK_CELL_EDITABLE (entry));
      gtk_cell_editable_remove_widget (GTK_CELL_EDITABLE (entry));

      return TRUE;
    }
[...]

Its a property. You shouldn't have any problems reading or writing it...