Gui: extend Workbench class to allow to define permanent menu items

src/Gui/MenuManager.cpp

@@ -84,6 +84,23 @@ MenuItem* MenuItem::findItem(const std::string& name)
     return 0;
 }
 
+MenuItem* MenuItem::findParentOf(const std::string& name)
+{
+    for (QList<MenuItem*>::Iterator it = _items.begin(); it != _items.end(); ++it)
+    {
+        if ((*it)->_name == name)
+            return this;
+    }
+
+    for (QList<MenuItem*>::Iterator it = _items.begin(); it != _items.end(); ++it)
+    {
+        if ((*it)->findParentOf(name))
+            return *it;
+    }
+
+    return nullptr;
+}
+
 MenuItem* MenuItem::copy() const
 {
     MenuItem* root = new MenuItem;