[gtk+] Protect gtk_text_view_scroll_mark_onscreen() from using invalid marks

[Kristian Rietveld <kristian src gnome org>]

commit a47aadb05ec83cecac777b31b03fba05504bc144
Author: Kristian Rietveld <kris gtk org>
Date:   Fri Sep 4 17:40:12 2009 +0200

    Protect gtk_text_view_scroll_mark_onscreen() from using invalid marks
    
    Suggested by Paolo Borelli.

 gtk/gtktextview.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtktextview.c b/gtk/gtktextview.c
index ad9cba0..0c41e24 100644
--- a/gtk/gtktextview.c
+++ b/gtk/gtktextview.c
@@ -2194,6 +2194,11 @@ gtk_text_view_scroll_mark_onscreen (GtkTextView *text_view,
   g_return_if_fail (GTK_IS_TEXT_VIEW (text_view));
   g_return_if_fail (GTK_IS_TEXT_MARK (mark));
 
+  /* We need to verify that the buffer contains the mark, otherwise this
+   * can lead to data structure corruption later on.
+   */
+  g_return_if_fail (get_buffer (text_view) == gtk_text_mark_get_buffer (mark));
+
   gtk_text_view_scroll_to_mark (text_view, mark, 0.0, FALSE, 0.0, 0.0);
 }