That's how EPiServer works OOTB. The page gets check out when someone starts to edit the page. The publish button and all fields gets diabled if another editor tries to edit the page. There should also be a small person icon next to the page in the page tree if someone is already editing the page.
Had not realised that it has changed from version 6 to be very obvious.
But I think that you can still create a new draft if the page is checked out.
I would like to know if there is an easy way to disable the CMS edit mode of a specific page if another user is already editing the page. Ideally we would like to see the edit mode grey out even while nagigating though the tree stucture so that it is very obvious.
We are aware that we can attach validators to stop users from publishing while some one else is edting, but would ideally like to stop them from modifying any fields. Once the first editor has published their changes it should be available to edit again.