Merge lp:~gordallott/nux/nux-fix-sigsevs into lp:nux

[Gord Allott]

Just fixes a few crashers in nux

=== modified file 'Nux/WindowThread.cpp'
--- Nux/WindowThread.cpp	2011-03-20 04:03:32 +0000
+++ Nux/WindowThread.cpp	2011-03-23 18:16:46 +0000
@@ -461,9 +461,27 @@
       return; 
     
     if (_focused_area != NULL)
+    {
       _focused_area->SetFocused (false);
+
+      if (_focused_area_destroyed_con.empty () == false)
+      {
+        _focused_area_destroyed_con.disconnect ();
+      }
+
+    }
     
     _focused_area = focused_area;
+    _focused_area_destroyed_con = focused_area->OnDestroyed.connect (sigc::mem_fun (this, &WindowThread::OnFocusedAreaDestroyed));
+    
+  }
+
+  void WindowThread::OnFocusedAreaDestroyed (Object *object)
+  {
+    if (object == _focused_area)
+    {
+      _focused_area = NULL;
+    }
   }
 
   void WindowThread::AsyncWakeUpCallback (void* data)
 
=== modified file 'Nux/WindowThread.h'
--- Nux/WindowThread.h	2011-03-17 14:47:06 +0000
+++ Nux/WindowThread.h	2011-03-23 18:16:46 +0000
@@ -469,7 +469,9 @@
     std::list< ThreadInfo * > m_ChildThreadInfo;
 
   private:
+    void OnFocusedAreaDestroyed (Object *object);
     Area *_focused_area;
+    sigc::connection _focused_area_destroyed_con;
     //! Informs the system of the start of a layout cycle.
     /*!
         This call merely sets a flag to true or false. This flag is used to decided if some actions should be 
 
=== modified file 'NuxImage/CairoGraphics.cpp'
--- NuxImage/CairoGraphics.cpp	2011-03-22 10:11:36 +0000
+++ NuxImage/CairoGraphics.cpp	2011-03-23 18:16:46 +0000
@@ -123,6 +123,13 @@
     t_u8 *ptr = cairo_image_surface_get_data (_cairo_surface);
     int stride = cairo_image_surface_get_stride (_cairo_surface);
 
+    if (ptr == NULL || stride == 0)
+    {
+      // _cairo_surface is not a valid surface
+      nuxError (TEXT ("[CairoGraphics::GetBitmap] Invalid surface"));
+      return bitmap_data; // just returns because we will segfault otherwise
+    }
+
     if (m_surface_format == CAIRO_FORMAT_A1)
     {
       t_u8 *temp = new t_u8[bitmap_data->GetSurface (0).GetPitch() ];