may still be editing TheWeb.TheTopic
The lease on this topic expired P3 ago.
The chances are good that P2 has simply navigated away from the edit page without saving.
You are encouraged to go ahead and edit - unless you intend to change data in a form attached to the topic. If P2 actually does
save while you are editing, your changes will be merged, and nothing will be lost. Form data cannot easily be merged though, so in this case you are recommended to check with P2 first.