[gtk+] treeview: Fix a rubberbanding-related crash

[Matthias Clasen <matthiasc src gnome org>]

commit d3adf47d9f70ed785dc26aba3b48e607f89ee5b5
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu May 19 16:59:10 2016 -0400

    treeview: Fix a rubberbanding-related crash
    
    When starting a rubberband selection from an empty area, we could run
    into crashes if the selection moves over the rows and then back out
    to unpopulated area. Handle this case without crashing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=766336

 gtk/gtktreeview.c |   55 +++++++++++++++++++++++++++++++++++++++-------------
 1 files changed, 41 insertions(+), 14 deletions(-)
---
diff --git a/gtk/gtktreeview.c b/gtk/gtktreeview.c
index 757e072..1ac81ca 100644
--- a/gtk/gtktreeview.c
+++ b/gtk/gtktreeview.c
@@ -4381,24 +4381,30 @@ gtk_tree_view_stop_rubber_band (GtkTreeView *tree_view)
       gtk_widget_queue_draw (GTK_WIDGET (tree_view));
 
       /* The anchor path should be set to the start path */
-      tmp_path = _gtk_tree_path_new_from_rbtree (tree_view->priv->rubber_band_start_tree,
-                                                tree_view->priv->rubber_band_start_node);
+      if (tree_view->priv->rubber_band_start_node)
+        {
+          tmp_path = _gtk_tree_path_new_from_rbtree (tree_view->priv->rubber_band_start_tree,
+                                                     tree_view->priv->rubber_band_start_node);
 
-      if (tree_view->priv->anchor)
-       gtk_tree_row_reference_free (tree_view->priv->anchor);
+          if (tree_view->priv->anchor)
+            gtk_tree_row_reference_free (tree_view->priv->anchor);
 
-      tree_view->priv->anchor =
-       gtk_tree_row_reference_new_proxy (G_OBJECT (tree_view),
-                                         tree_view->priv->model,
-                                         tmp_path);
+          tree_view->priv->anchor =
+            gtk_tree_row_reference_new_proxy (G_OBJECT (tree_view),
+                                              tree_view->priv->model,
+                                              tmp_path);
 
-      gtk_tree_path_free (tmp_path);
+          gtk_tree_path_free (tmp_path);
+        }
 
       /* ... and the cursor to the end path */
-      tmp_path = _gtk_tree_path_new_from_rbtree (tree_view->priv->rubber_band_end_tree,
-                                                 tree_view->priv->rubber_band_end_node);
-      gtk_tree_view_real_set_cursor (GTK_TREE_VIEW (tree_view), tmp_path, 0);
-      gtk_tree_path_free (tmp_path);
+      if (tree_view->priv->rubber_band_end_node)
+        {
+          tmp_path = _gtk_tree_path_new_from_rbtree (tree_view->priv->rubber_band_end_tree,
+                                                     tree_view->priv->rubber_band_end_node);
+          gtk_tree_view_real_set_cursor (GTK_TREE_VIEW (tree_view), tmp_path, 0);
+          gtk_tree_path_free (tmp_path);
+        }
 
       _gtk_tree_selection_emit_changed (tree_view->priv->selection);
 
@@ -4535,7 +4541,28 @@ gtk_tree_view_update_rubber_band_selection (GtkTreeView *tree_view)
   _gtk_rbtree_find_offset (tree_view->priv->tree, MAX (tree_view->priv->press_start_y, bin_y), &end_tree, 
&end_node);
 
   /* Handle the start area first */
-  if (!tree_view->priv->rubber_band_start_node)
+  if (!start_node && !end_node)
+    {
+      if (tree_view->priv->rubber_band_start_node)
+        {
+          GtkRBNode *node = tree_view->priv->rubber_band_start_node;
+          GtkRBTree *tree = tree_view->priv->rubber_band_start_tree;
+
+         if (tree_view->priv->rubber_band_modify)
+           {
+             /* Toggle the selection state */
+             if (GTK_RBNODE_FLAG_SET (node, GTK_RBNODE_IS_SELECTED))
+               GTK_RBNODE_UNSET_FLAG (node, GTK_RBNODE_IS_SELECTED);
+             else
+               GTK_RBNODE_SET_FLAG (node, GTK_RBNODE_IS_SELECTED);
+           }
+          else
+            GTK_RBNODE_UNSET_FLAG (node, GTK_RBNODE_IS_SELECTED);
+
+          _gtk_tree_view_queue_draw_node (tree_view, tree, node, NULL);
+        }
+    }
+  if (!tree_view->priv->rubber_band_start_node || !start_node)
     {
       gtk_tree_view_update_rubber_band_selection_range (tree_view,
                                                       start_tree,