missed the windowproc return value

git-svn-id: https://svn.code.sf.net/p/freeglut/code/trunk@1547 7f0cb862-5218-0410-a997-914c9d46530a

freeglut/freeglut/src/mswin/fg_main_mswin.c

@@ -663,6 +663,7 @@ LRESULT CALLBACK fgPlatformWindowProc( HWND hWnd, UINT uMsg, WPARAM wParam, LPAR
             fghRedrawWindow( window );
             EndPaint( hWnd, &ps );
         }
+        lRet = 0;   /* As per docs, should return 0 */
     }
     break;