81) What is the best way to create popup menus?

[Last modified: August 92]

Susan Murdock Thompson (from OSF): In general, create a popupMenu as the child
from which you will be posting it from (ie: if you have a bulletinBoard with a
PushButton in it and want MB2 on the pushButton to post the popupMenu, create
the popupMenu as a child of the pushButton).  [This parent-child relationship
seems to make a big difference in the behavior of the popups.]  Add an event
handler to handle buttonPress events.  You'll need to check for the correct
button (what you've specified menuPost to be) before posting the menu.

To create a popup that can be accessible from within an entire client window,
create it as the child of the top-most widget (but not the shell) and add
event handlers for the top-most widget and children widgets.

ie:

{
  ....

  XtManageChild(rc=XmCreateRowColumn(Shell1, "rc", NULL, 0));
  XtManageChild(label = XmCreateLabel(rc, "label", NULL, 0));
  XtManageChild(text = XmCreateText(rc, "text", NULL, 0));
  XtManageChild(pushbutton = XmCreatePushButton(rc, "pushbutton", NULL, 0));

  n = 0;
  XtSetArg(args[n], XmNmenuPost, "<Btn3Down>"); n++;
  popup = XmCreatePopupMenu(rc, "popup", args, n);

  XtAddEventHandler(rc, ButtonPressMask, False, PostMenu3, popup);
  XtAddEventHandler(text, ButtonPressMask, False, PostMenu3, popup);
  XtAddEventHandler(label, ButtonPressMask, False, PostMenu3, popup);
  XtAddEventHandler(pushbutton, ButtonPressMask, False, PostMenu3, popup);

  XtManageChild(m1 = XmCreatePushButton(popup, "m1", NULL, 0));
  XtManageChild(m2 = XmCreatePushButton(popup, "m2", NULL, 0));
  XtManageChild(m3 = XmCreatePushButton(popup, "m3", NULL, 0));

  XtAddCallback(m1, XmNactivateCallback, SayCB, "button M1");
  XtAddCallback(m2, XmNactivateCallback, SayCB, "button M2");
  XtAddCallback(m3, XmNactivateCallback, SayCB, "button M3");
  ...
}

/* where PostMenu3 is ... */

PostMenu3 (w, popup, event)
Widget w;
Widget popup;
XButtonEvent * event;
{
  printf("menuPost = 3, button %d0, event->button);

  if (event->button != Button3)
    return;
  XmMenuPosition(popup, event);
  XtManageChild(popup);
}