[gtk+/treeview-refactor] Fix GtkCellAreaBox allocate_cells_manually to handle undersized areas.

[Tristan Van Berkom <tvb src gnome org>]

commit 9366a345b47bfb64f1e237392209a71d13114053
Author: Tristan Van Berkom <tristan van berkom gmail com>
Date:   Mon Dec 6 16:29:40 2010 +0900

    Fix GtkCellAreaBox allocate_cells_manually to handle undersized areas.

 gtk/gtkcellareabox.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkcellareabox.c b/gtk/gtkcellareabox.c
index 62db9b5..e977679 100644
--- a/gtk/gtkcellareabox.c
+++ b/gtk/gtkcellareabox.c
@@ -697,7 +697,10 @@ allocate_cells_manually (GtkCellAreaBox        *box,
 
   /* Naturally distribute the allocation */
   avail_size -= (nvisible - 1) * priv->spacing;
-  avail_size = gtk_distribute_natural_allocation (avail_size, nvisible, sizes);
+  if (avail_size > 0)
+    avail_size = gtk_distribute_natural_allocation (avail_size, nvisible, sizes);
+  else
+    avail_size = 0;
 
   /* Calculate/distribute expand for cells */
   if (nexpand > 0)