Lock the root menu before calling BMenuItem::Invoke(). This fixes #3842, although in some circumstances could introduce a deadlock (if someone does strange things in Invoke(), for example).

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30662 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/kits/interface/Menu.cpp

@@ -2279,7 +2279,18 @@ BMenu::_InvokeItem(BMenuItem *item, bool now)
 		UnlockLooper();
 	}
 
-	item->Invoke();
+	// Lock the root menu window before calling BMenuItem::Invoke()
+	BMenu *parent = this;
+	BMenu *rootMenu = NULL;
+	do {
+		rootMenu = parent;
+		parent = rootMenu->Supermenu();
+	} while (parent != NULL);
+		
+	if (rootMenu->LockLooper()) {
+		item->Invoke();
+		rootMenu->UnlockLooper();
+	}
 }