Added something to suppress warnings from visual studio.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402733

dlib/matrix/matrix_expressions.h

@@ -5,6 +5,17 @@
 
 #include "matrix_fwd.h"
 
+#ifdef _MSC_VER
+// This #pragma directive is also located in the algs.h file but for whatever
+// reason visual studio 9 just ignores it when it is only there. 
+
+// this is to disable the "'this' : used in base member initializer list"
+// warning you get from some of the GUI objects since all the objects
+// require that their parent class be passed into their constructor. 
+// In this case though it is totally safe so it is ok to disable this warning.
+#pragma warning(disable : 4355)
+#endif
+
 namespace dlib
 {