Send WM_HELP message when F1 is pressed.

diff --git a/windows/defwnd.c b/windows/defwnd.c
index 2b70936..e7b5705 100644
--- a/windows/defwnd.c
+++ b/windows/defwnd.c
@@ -481,6 +481,9 @@
 
             return result;
         }
+    case WM_HELP:
+	SendMessageA( wndPtr->parent->hwndSelf, msg, wParam, lParam );
+	break;
     }
 
     return 0;