[gtk+] treeview: check for pixel cache before setting property

[Christian Hergert <chergert src gnome org>]

commit b37400752bdc282888e13c9d74aa3e904bab8283
Author: Christian Hergert <christian hergert me>
Date:   Thu Aug 20 11:13:30 2015 -0700

    treeview: check for pixel cache before setting property
    
    Code exists in the wild that calls this function after the widget has
    been destroyed (and the pixel cache released). Simply check that the
    pixel cache exists to preserve the existing state.

 gtk/gtktreeview.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtktreeview.c b/gtk/gtktreeview.c
index a0286a7..6de8ff2 100644
--- a/gtk/gtktreeview.c
+++ b/gtk/gtktreeview.c
@@ -11541,7 +11541,8 @@ gtk_tree_view_set_model (GtkTreeView  *tree_view,
   if (tree_view->priv->selection)
   _gtk_tree_selection_emit_changed (tree_view->priv->selection);
 
-  _gtk_pixel_cache_set_always_cache (tree_view->priv->pixel_cache, (model != NULL));
+  if (tree_view->priv->pixel_cache != NULL)
+    _gtk_pixel_cache_set_always_cache (tree_view->priv->pixel_cache, (model != NULL));
 
   if (gtk_widget_get_realized (GTK_WIDGET (tree_view)))
     gtk_widget_queue_resize (GTK_WIDGET (tree_view));