Being able to sort and group objects would be nice. Like being able to create folders or collapsable tree nodes to put objects into.
Along the same lines, perhaps these folders or nodes can have a toggle option to include/exclude the objects in them from the event sheet dialogues. Like, if you have a whole folder of background tiles that do nothing but sit there in the layout and you don't ever need to perform any actions on them, they wouldn't clutter things up when creating events.
Pretty sure both of those have been requested before.