[gtk+] gtk: fix crash in _gtk_rbtree_find_offset() called from update_prelight()

[Michael Natterer <mitch src gnome org>]

commit 07dc2f6c35cbe1909f6194ffe8dafdd7c82a9380
Author: Michael Natterer <mitch gimp org>
Date:   Sat Feb 6 15:57:15 2010 +0100

    gtk: fix crash in _gtk_rbtree_find_offset() called from update_prelight()
    
    Move the check for tree_view->priv->tree being NULL into update_prelight()
    so the function will never call _gtk_rbtree_find_offset() on a NULL rbtree.

 gtk/gtktreeview.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtktreeview.c b/gtk/gtktreeview.c
index 1b14f7b..fe815d2 100644
--- a/gtk/gtktreeview.c
+++ b/gtk/gtktreeview.c
@@ -3318,6 +3318,9 @@ update_prelight (GtkTreeView *tree_view,
   GtkRBTree *tree;
   GtkRBNode *node;
 
+  if (tree_view->priv->tree == NULL)
+    return;
+
   if (x == -10000)
     {
       ensure_unprelighted (tree_view);
@@ -10572,10 +10575,9 @@ gtk_tree_view_adjustment_changed (GtkAdjustment *adjustment,
       dy = tree_view->priv->dy - (int) tree_view->priv->vadjustment->value;
       if (dy)
 	{
-          if (tree_view->priv->tree)
-            update_prelight (tree_view,
-                             tree_view->priv->event_last_x,
-                             tree_view->priv->event_last_y - dy);
+          update_prelight (tree_view,
+                           tree_view->priv->event_last_x,
+                           tree_view->priv->event_last_y - dy);
 
 	  if (tree_view->priv->edited_column &&
               GTK_IS_WIDGET (tree_view->priv->edited_column->editable_widget))