Wow. I just noticed an FMP behavior that I was completely unaware of until today. Ordinarily, in a list layout, if you're viewing a certain found set, and another user adds a record that technically "belongs" to your found set, FileMaker does not update the layout, presumably because FileMaker considers your found set to be sacred and not to be messed with, forcing the developer to use "On Timer" script steps to make the layout refresh automatically.
I just noticed (accidentally) that when the found set is "Show All Records", list layouts do indeed dynamically refresh, with no developer intervention. Does anyone know how long this has been FMP's behavior? Is it a recent enhancement, or have I just been out of the loop?