[gtk+] Protect against tree_view being NULL

[Matthias Clasen <matthiasc src gnome org>]

commit 99691ab7aa61fd7aa702b90f181e9793c1ea2947
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Feb 2 23:54:38 2011 -0500

    Protect against tree_view being NULL
    
    This apparently happens when setting the "visible" property
    from ui files.
    https://bugzilla.gnome.org/show_bug.cgi?id=640801

 gtk/gtktreeviewcolumn.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/gtk/gtktreeviewcolumn.c b/gtk/gtktreeviewcolumn.c
index de1a0a2..b9f1899 100644
--- a/gtk/gtktreeviewcolumn.c
+++ b/gtk/gtktreeviewcolumn.c
@@ -1891,10 +1891,10 @@ gtk_tree_view_column_get_spacing (GtkTreeViewColumn *tree_column)
  * @visible: %TRUE if the @tree_column is visible.
  * 
  * Sets the visibility of @tree_column.
- **/
+ */
 void
 gtk_tree_view_column_set_visible (GtkTreeViewColumn *tree_column,
-				  gboolean           visible)
+                                  gboolean           visible)
 {
   GtkTreeViewColumnPrivate *priv;
 
@@ -1902,7 +1902,7 @@ gtk_tree_view_column_set_visible (GtkTreeViewColumn *tree_column,
 
   priv    = tree_column->priv;
   visible = !! visible;
-  
+
   if (priv->visible == visible)
     return;
 
@@ -1911,7 +1911,8 @@ gtk_tree_view_column_set_visible (GtkTreeViewColumn *tree_column,
   if (priv->visible)
     _gtk_tree_view_column_cell_set_dirty (tree_column, TRUE);
 
-  _gtk_tree_view_reset_header_styles (GTK_TREE_VIEW (priv->tree_view));
+  if (priv->tree_view)
+    _gtk_tree_view_reset_header_styles (GTK_TREE_VIEW (priv->tree_view));
 
   gtk_tree_view_column_update_button (tree_column);
   g_object_notify (G_OBJECT (tree_column), "visible");