[andoando]

Regarding security: I think this is already managed in the iOS/Android ecosystem. It shouldn't be too difficult to restrict permissions from sites, and has the advantage of possibly allowing accesses for sites you trust.

Regardling difficulty: HTML/CSS is essentially already cross platform UI toolkit. Yes its hard, but Im saying if one were to make it, I dont see why the same UI framework shouldnt work for a desktop application.

[n4te]

True those platforms have security controls, better than what we've ever seen on desktop. Desktop also needs controls like that: to use the system tray, filesystem, hardware, etc. There's at least a work multiplier of 3 for Windows, Mac, Linux. It's just one of many things needed.

Building the web toolkit took enormous effort and it sucks in many ways (see article). Theoretically a new one could be created and could also work for desktop, but there are lots of reasons why that won't happen.