>Wrt your reference to "browser tab", our experience was that the tab needs to be sized across 2 or more monitors if we wanted to distribute its contents across 2 or more monitors. The issue arises when you also want other apps including email and Messsenger between app panels, as customers say they want all the time.

Not sure I am understanding the problem - if the user wants, say, 20 windows open and can only see them all in the browser tab if he opens/resizes the browser across 2 screens that is their choice. If they want to have some of the windows open on one screen and some on another screen then the user would simply open 2 browsers (or drag a tab off into its own browser window) and size/position each accordingly. In this prototype proof-of-concept solution the user can open as many tabs, each containing as many windows as they like, and each tab can be in a single parent browser window or dragged off into its own browser parent window ! ... Maybe I don’t understand the problem scenario?

>IME browser apps (and device apps) are more attuned towards a single Window and inter-window communication is problematic, e.g. if a hacker can get something into an off-screen Window snooping on your online banking session, which was one of the risks why MS said they blocked the technique we used. Like you, we've gone to some trouble to offer a windows alternative. - J

Yeah, not a problem in this prototype solution we built. The whole this is a dynamic website and only subject to the usual website security issues. No known way to hijack the WebDev website that I have heard of unless the server is compromised I guess - but that is a threat to any website server.