Ah, I see - so I can remove the CF.activity().onExit line again?
I've now put

CF.page().onExit = function() { close(); }

after all the ".visible = true" lines instead, which doesn't seem to not work - at least in the simulator.
Reading your function's comments, I'm wondering what kind of issues I should expect with calling close() directly?
I am assuming it's because objects are already being dereferenced by the system while the onExit callback function is being executed?
So should I generally use something like "CF.page()['___myDialog'] = this; ..." or only in case when issues become noticeable?

Also I noticed that you're often putting something like "this.onExit = null;" at the end to remove the callback - is this just to help the garbage collector along?

Sebastian