add notice for archived threads at top of chatwindow

components/chatwindow.hpp

@@ -28,6 +28,7 @@ public:
     void InsertChatInput(std::string text);
     Snowflake GetOldestListedMessage(); // oldest message that is currently in the ListBox
     void UpdateReactions(Snowflake id);
+    void SetTopic(const std::string &text);
 
 protected:
     bool m_is_replying = false;
@@ -49,6 +50,9 @@ protected:
     //Gtk::ListBox *m_list;
     //Gtk::ScrolledWindow *m_scroll;
 
+    Gtk::EventBox m_topic; // todo probably make everything else go on the stack
+    Gtk::Label m_topic_text;
+
     ChatList *m_chat;
 
     ChatInput *m_input;