Is it possible to reset variable values when closing a popup window? I have not seen any type of closing event on the popup which would prompt code to reset variables used in the popup.
When a Vision popup closes, it ceases to exist, so there's nothing to reset.
(If cached, it doesn't completely cease to exist, but binding initialization happens from scratch when re-opened.)
If you want to ensure constant initial values on open, the most reliable technique is to have constant expression bindings on those properties. Such bindings only run once, on component startup.