add some dx checking routines to the dx plugin + some minor stuff

git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@5466 8ced0084-cf51-0410-be5f-012b33b47a6e

Source/Plugins/Plugin_VideoDX9/Src/W32Util/PropertySheet.h

@@ -12,6 +12,7 @@ namespace W32Util
 		PropSheet *sheet; //back pointer ..
 		virtual void Init(HWND hDlg) {}
 		virtual void Command(HWND hDlg, WPARAM wParam) {}
+		virtual int Notify(HWND, LPARAM) {return 0;}
 		virtual void Apply(HWND hDlg) {}
 		virtual bool HasPrev()   {return true;}
 		virtual bool HasFinish() {return false;}