Default top level menu on each recreation

Make sure 'Edit' isn't left shaded by a previous TaskWindow opening.
Retagged as RISC_OSLib-5_85.

rlib/c/txtedit

@@ -648,6 +648,7 @@ static menu txtedit_menumaker(void *a) {
   txtwin_setcurrentwindow(s->t);
   if (txtedit__menu == 0) txtedit__menumaker(a);
   help_register_handler(txtedit__help_handler, s);
+  menu_setflags(txtedit__menu, txtedit_MEdit, FALSE, FALSE);
 
   /* Place ticks where required */
   menu_setflags(m1, txtedit_MOverwrite, s->overwrite, FALSE);