Does anyone know of an extension or plugin that makes it possible to lock attachments for editing, kind of like the checkout feature for Sharepoint? I know there are an extension for Confluence that makes this possible.
The reason for the request is that we have users that would like to checkout a document for offline editing and make sure no other edit the document until they upload it again. have searched extensively, but not found any solutions for xwiki.
By default XWiki puts a lock when someone edits a page so you do have a lock on attachments too, see http://www.xwiki.org/xwiki/bin/view/Documentation/UserGuide/Features/PageEditing#HLocking (documentation just added, was missing :)).
Since attachements are modified in view mode I’m not so sure they check for the lock.
hmm that’s a good point… I guess they probably should.
Not really sure if I am understanding this correctly.
Let’s say we have an Excel file attached to a page. User A download attachment to local computer and want to edit at home. During that time someone in the office, User B works with the attachment, now we have two different versions of the same file. When user A get back to work he uploads the document, writing over user B’s changes.
What I would like is the possibility for user A to flag the file as locked for editing. Will editing the page solves this? Do you mean that if user A press Edit on the page before leaving, and not pressing save, the page will be locked?
This could be a solution, although not the best one 
Thanks for helping.
No that won’t work. The lock will remain for 30 minutes only.
The best solution I can think for this is to use the OnlyOffice extension which supports realtime and thus concurrent editing and thus automatic merges.
Note that it’s a paying app: https://store.xwiki.com/xwiki/bin/view/Extension/OnlyOfficeConnectorApplication