Motif: bug in MenuShell

[tlaronde%polynum.com@localhost]

Hello,

Here is a small patch to correct a bug in MenuShell: when the position
of a a menu to display is computed, management is done for certain types
in order for the menu to do appear on the display (is position not
putting it partly or totally outside).

The code is using RC_Type() that expects a RowColumn widget. It has to
be verified first (previous code in the same function is doing it
correctly).

For the package and to push upstream?

Best,
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
Key fingerprint = 0FF7 E906 FBAF FE95 FD89  250D 52B1 AE95 6006 F40C

--- lib/Xm/MenuShell.c.old	2023-04-24 08:55:13.262223558 +0200
+++ lib/Xm/MenuShell.c	2023-04-24 08:56:49.071077100 +0200
@@ -988,6 +988,7 @@
    if (bottomEdgeOfMenu >= (Position)dispHeight)
    {
       if (pulldown_button && XtParent(pulldown_button) &&
+		XmIsRowColumn(XtParent(pulldown_button)) &&
 	  (RC_Type(XtParent(pulldown_button)) == XmMENU_BAR))
       {
 	 Position y_temp = *y;