WindowServer+LibGUI: Automatically close child windows with parent

If a window has child windows when it's destroyed, WindowServer will
now automatically tear down all of its children as well.

This is communicated to the client program through a vector of window
ID's included with the response to WindowServer::DestroyWindow.

This does feel a little bit awkward, but managing it on the client side
also seems a bit awkward.

3 files changed, 28 insertions, 10 deletions

diff --git a/Servers/WindowServer/ClientConnection.cpp b/Servers/WindowServer/ClientConnection.cpp
index 32b2ba3100..e49143d700 100644
--- a/Servers/WindowServer/ClientConnection.cpp
+++ b/Servers/WindowServer/ClientConnection.cpp
@@ -472,6 +472,10 @@ OwnPtr<Messages::WindowServer::CreateWindowResponse> ClientConnection::handle(co
             did_misbehave("CreateWindow with bad parent_window_id");
             return nullptr;
         }
+        if (parent_window->window_id() == window_id) {
+            did_misbehave("CreateWindow trying to make a window with itself as parent");
+            return nullptr;
+        }
         window->set_parent_window(*parent_window);
     }
 
@@ -497,24 +501,36 @@ OwnPtr<Messages::WindowServer::CreateWindowResponse> ClientConnection::handle(co
     return make<Messages::WindowServer::CreateWindowResponse>(window_id);
 }
 
-OwnPtr<Messages::WindowServer::DestroyWindowResponse> ClientConnection::handle(const Messages::WindowServer::DestroyWindow& message)
+void ClientConnection::destroy_window(Window& window, Vector<i32>& destroyed_window_ids)
 {
-    auto it = m_windows.find(message.window_id());
-    if (it == m_windows.end()) {
-        did_misbehave("DestroyWindow: Bad window ID");
-        return nullptr;
+    for (auto& child_window : window.child_windows()) {
+        if (!child_window)
+            continue;
+        ASSERT(child_window->window_id() != window.window_id());
+        destroy_window(*child_window, destroyed_window_ids);
     }
-    auto& window = *(*it).value;
+
+    destroyed_window_ids.append(window.window_id());
 
     if (window.type() == WindowType::MenuApplet)
         AppletManager::the().remove_applet(window);
 
     WindowManager::the().invalidate(window);
     remove_child(window);
-    ASSERT(it->value.ptr() == &window);
-    m_windows.remove(message.window_id());
+    m_windows.remove(window.window_id());
+}
 
-    return make<Messages::WindowServer::DestroyWindowResponse>();
+OwnPtr<Messages::WindowServer::DestroyWindowResponse> ClientConnection::handle(const Messages::WindowServer::DestroyWindow& message)
+{
+    auto it = m_windows.find(message.window_id());
+    if (it == m_windows.end()) {
+        did_misbehave("DestroyWindow: Bad window ID");
+        return nullptr;
+    }
+    auto& window = *(*it).value;
+    Vector<i32> destroyed_window_ids;
+    destroy_window(window, destroyed_window_ids);
+    return make<Messages::WindowServer::DestroyWindowResponse>(destroyed_window_ids);
 }
 
 void ClientConnection::post_paint_message(Window& window, bool ignore_occlusion)
diff --git a/Servers/WindowServer/ClientConnection.h b/Servers/WindowServer/ClientConnection.h
index 1c11bb2711..92c2f2fa08 100644
--- a/Servers/WindowServer/ClientConnection.h
+++ b/Servers/WindowServer/ClientConnection.h
@@ -79,6 +79,8 @@ public:
 private:
     explicit ClientConnection(Core::LocalSocket&, int client_id);
 
+    void destroy_window(Window&, Vector<i32>& destroyed_window_ids);
+
     virtual OwnPtr<Messages::WindowServer::GreetResponse> handle(const Messages::WindowServer::Greet&) override;
     virtual OwnPtr<Messages::WindowServer::CreateMenubarResponse> handle(const Messages::WindowServer::CreateMenubar&) override;
     virtual OwnPtr<Messages::WindowServer::DestroyMenubarResponse> handle(const Messages::WindowServer::DestroyMenubar&) override;
diff --git a/Servers/WindowServer/WindowServer.ipc b/Servers/WindowServer/WindowServer.ipc
index d1be40824a..214afa7567 100644
--- a/Servers/WindowServer/WindowServer.ipc
+++ b/Servers/WindowServer/WindowServer.ipc
@@ -44,7 +44,7 @@ endpoint WindowServer = 2
         String title,
         i32 parent_window_id) => (i32 window_id)
 
-    DestroyWindow(i32 window_id) => ()
+    DestroyWindow(i32 window_id) => (Vector<i32> destroyed_window_ids)
 
     SetWindowTitle(i32 window_id, String title) => ()
     GetWindowTitle(i32 window_id) => (String title)