How to coordinate drawing access remotely among shared users

[FurnitureGal]

Hi -

I'm working on a project with multiple users who are located in different parts of the country. We've set up a dropbox site for our drawings.

 

We are stumped on how to avoid the issue of multiple users accessing the same document. Apparently on Dropbox the access is not limited; so others can use it and modify it - at the same time. This is a huge problem; would appreciate any insight.

[CyberAngel]

Is there no way at all to make a file read-only? That sort of defeats the purpose of a drop box.