Note that if your handler runs before the default handler
it must not invalidate the @location iter (or has to
revalidate it). The default signal handler revalidates
it to point to the end of the inserted text.
See also: [method@Gtk,TextBuffer.insert],
[method@Gtk.TextBuffer.insert_range].
Emitted to insert text in a GtkTextBuffer.
Insertion actually occurs in the default handler.
Note that if your handler runs before the default handler it must not invalidate the @location iter (or has to revalidate it). The default signal handler revalidates it to point to the end of the inserted text.
See also: [method@Gtk,TextBuffer.insert], [method@Gtk.TextBuffer.insert_range].