This is a follow up on
How to reproduce?
1) build a plain vanilla alfresco 4.0 (tomcat, linux, mysql)
2) as 'admin' in alfresco explorer create two users 'user1' and 'user2'
3) as 'admin' create a folder 'folder1' and invite 'user1' and 'user2' as collaborator
4) as 'user1' upload a file 'test.txt' in 'folder1'
5) as 'user1' check out 'test.txt'
6) as 'user2' try to edit the checked-out document in explorer
this is NOT possible (see screen shots)
user2 should be able to edit the working copy as per