Collaborative editing - Multiple users editing a document simultaneously

In the current version of Zoho Writer, we lock a shared document when one of the shared users is editing it. Lots of users want to have collaborative editing i.e multiple users editing the same file at the same time. Through collaborative editing, users get to realise the full true power of collaboration of a web based application. We are working on this and the initial cut has come out very well. Following is what we plan to do:

— When a shared document is opened, we will be showing all the users who are currently viewing / editing the document in the left navigation pane
— Each user edit area will be blocked. So, more than one user will be allowed to edit & each user will know the block area being edited by the other user(s)
— Also, we plan to have a notification pop-up when someone is shared a document