diff -up mhgui-0.2/include/mhgui/ImageData.h.png15 mhgui-0.2/include/mhgui/ImageData.h

--- mhgui-0.2/include/mhgui/ImageData.h.png15	2007-12-12 22:07:20.000000000 +0100

+++ mhgui-0.2/include/mhgui/ImageData.h	2012-01-21 15:10:13.179933285 +0100

@@ -67,7 +67,7 @@ class ImageData

 private:

   char         *image_data; /* raw png image data */

   char         *end_bufferPtr;

-  unsigned long width, height;

+  png_uint_32   width, height;

   unsigned int  bytesPerRow;

   bool          alpha;