(update_one_menu_entry): When creating a pulldown

in an existing but empty menu item, in order to get a new functional
pulldown, the menu item must be switched from an XmPushButtonGadget
into a XmCascadeButtonGadget.

1 files changed, 36 insertions, 3 deletions

diff --git a/lwlib/lwlib-Xm.c b/lwlib/lwlib-Xm.c
index c5da97f85ed..38713adb25f 100644
--- a/lwlib/lwlib-Xm.c
+++ b/lwlib/lwlib-Xm.c
@@ -509,11 +509,41 @@ update_one_menu_entry (instance, widget, val, deep_p)
     {
       if (contents)
         {
-          menu = XmCreatePulldownMenu (XtParent (widget), XtName (widget), NULL, 0);
+          unsigned int old_num_children, i;
+          Widget button, parent;
+          Widget *widget_list;
+          int buttonchange;
+
+          parent = XtParent (widget);
+          widget_list = XtCompositeChildren (parent, &old_num_children);
+
+          /* Find the widget position within the parent's widget list.  */
+          for (i = 0; i < old_num_children; i++)
+            if (strcmp (XtName (widget_list[i]), XtName (widget)) == 0)
+              break;
+          if (i == old_num_children)
+            abort ();
+          /* `buttonchange' indicates the parent button is being
+             exchanged with a CascadeButton.  */
+          buttonchange = !XmIsCascadeButton (widget_list[i]);
+          if (buttonchange)
+            XtDestroyWidget (widget_list[i]);
+          menu = XmCreatePulldownMenu (parent, val->name, NULL, 0);
           make_menu_in_widget (instance, menu, contents, 0);
           ac = 0;
           XtSetArg (al [ac], XmNsubMenuId, menu); ac++;
-          XtSetValues (widget, al, ac);
+          /* Non-zero values don't work reliably in
+             conjunction with Emacs' event loop */
+          XtSetArg (al [ac], XmNmappingDelay, 0); ac++;
+          /* Tell Motif to put it in the right place.  */
+          XtSetArg (al [ac], XmNpositionIndex, i); ac++;
+          button = XmCreateCascadeButtonGadget (parent, val->name, al, ac);
+          xm_update_label (instance, button, val);
+          
+          XtAddCallback (button, XmNcascadingCallback, xm_pull_down_callback,
+                         (XtPointer)instance);
+          if (buttonchange)
+            XtManageChild (button);
         }
     }
   else if (!contents)
@@ -575,7 +605,10 @@ xm_update_menu (instance, widget, val, deep_p)
       for (i = 0, cur = val->contents; i < num_children_to_keep; i++)
         {
           if (!cur)
-            abort ();
+            {
+              num_children_to_keep = i;
+              break;
+            }
           if (children [i]->core.being_destroyed
               || strcmp (XtName (children [i]), cur->name))
             continue;