One of the new core features in PostNuke .8 is the "PageLock" module. This module can be used to restrict access to a certain page in such a way that only one user at a time has access to it. This can be used to avoid our classic concurrency problem:
If we add a page locking feature to the editing page then this would happen instead:
This is what the PageLock module will do for you. When user A opens his window it will register it and start pinging the server (using AJAX) every X sec. to ensure the lock is kept. When user B opens his window then it is blocked, but keep pinging the server (also using AJAX) until user A releases the lock.
If you want to use this feature in your modules then please read more in the wiki.
The PageLock module has not yet been used in any of the AddOns modules except the HowToPnForms demo module. The reason is that it potentially may break something and we don't want yet another feature to postpone the .8 release.