[regexxer] Check for null pointer when scrolling.

[Fabien Parent <fparent src gnome org>]

commit 2578dedb92c05318c9d8f09165b8a17ef1aacdab
Author: Fabien Parent <parent f gmail com>
Date:   Sat Jul 16 15:26:32 2011 +0200

    Check for null pointer when scrolling.

 src/mainwindow.cc |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/mainwindow.cc b/src/mainwindow.cc
index 8cd4b26..0277761 100644
--- a/src/mainwindow.cc
+++ b/src/mainwindow.cc
@@ -785,6 +785,9 @@ void MainWindow::on_go_next_file(bool move_forward)
 
 bool MainWindow::do_scroll(const Glib::RefPtr<Gtk::TextMark> mark)
 {
+  if (!mark)
+    return false;
+
   textview_->scroll_to(mark, 0.125);
   return false;
 }