[perl-Gtk2] Gtk2::CellLayout::get_cells: document unusual return semantics

[Torsten SchÃnfeld <tsch src gnome org>]

commit 1a20171f8a30357b62ce06f1ace0b8bacfc37d05
Author: Torsten SchÃnfeld <kaffeetisch gmx de>
Date:   Mon Oct 3 17:04:53 2011 +0200

    Gtk2::CellLayout::get_cells: document unusual return semantics
    
    https://bugzilla.gnome.org/show_bug.cgi?id=629727

 xs/GtkCellLayout.xs |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/xs/GtkCellLayout.xs b/xs/GtkCellLayout.xs
index 6df83f2..12883f6 100644
--- a/xs/GtkCellLayout.xs
+++ b/xs/GtkCellLayout.xs
@@ -471,6 +471,9 @@ void gtk_cell_layout_reorder (GtkCellLayout *cell_layout, GtkCellRenderer *cell,
 
 =for apidoc
 Fetch all of the cell renderers which have been added to I<$cell_layout>.
+
+Note that if there are no cells this functions returns 'undef' instead of an
+empty list.
 =cut
 void
 gtk_cell_layout_get_cells (GtkCellLayout *cell_layout)