I know you can send messages to a canvas to create objects, move things, make connections, etc.
Is there conversely a way to receive messages from a canvas? For example, can you get a message when an object is created or moved?
The use case I am specifically after right now is to create a conditional that checks if a subpatch is open or not. I can send vis 1 to the subpatch to open the window, but can I receive a vis 1 or vis 0 (or some other equivalent notification) when the window is opened or closed by other means?