Suppose I have a file on my folder checked by subversion.
Now, If I start to edit the file (I mean, I see the yellow cue ball on it) I'd like that other people that can access to this file through svn can't open and edit it.
Is it possible?
You can request a lock on it. People would be able to edit their local copy but can't commit until lock is release. So they need to wait for your commit, then update/merge and commit after that.
If this is difficult file type to merge, it would be good that everybody request lock on the file before starting any modification, so that if someone has already a lock, other user would know that prior to edition.