diff --git a/todo.md b/todo.md
index 7d9e5f9..309b34d 100644
--- a/todo.md
+++ b/todo.md
@@ -24,6 +24,7 @@ so I don't forget:
 important things:
 - there's no GTK+ error handling whatsoever; we need to figure out how it works
 - make sure GTK+ documentation point differences don't matter
+- lock setRect() and preferredSize() in all Controls (including Stack)
 
 super ultra important things:
 - for some reason events are now delayed on windows