Why Dropbox file locking doesn't work?
For file locking to work properly, the software needs to know the user's intent first (such as double click on a file), and then check the conditions such as whether or not the user has access permission or the file has been locked. When all the conditions are checked, it is OK now to serve the file or reject the intent. This is why the virtual drive mapper is very important because it knows the user is trying to open the file before the file is served to the user.
However, in the Dropbox's case, the files and folders are already synchronized into the user's local Dropbox folder. Once it is local, the end user can do whatever they want to do to the files, file locking becomes an after thought and thus there is no Dropbox file locking for local files. You can shutdown the Dropbox desktop agent and you can manipulate those files, disregarding file locking completely.
