Forgot to change tab_ref when attaching window

kitty/tabs.py

@@ -324,8 +324,7 @@ class Tab:  # {{{
         return underlaid_window, overlaid_window
 
     def attach_window(self, window):
-        window.tab_id = self.id
-        window.os_window_id = self.os_window_id
+        window.change_tab(self)
         attach_window(self.os_window_id, self.id, window.id)
         self._add_window(window)
 

kitty/window.py

@@ -163,6 +163,11 @@ class Window:
         else:
             setup_colors(self.screen, opts)
 
+    def change_tab(self, tab):
+        self.tab_id = tab.id
+        self.os_window_id = tab.os_window_id
+        self.tabref = weakref.ref(tab)
+
     @property
     def title(self):
         return self.override_title or self.child_title