Can you be more exact what you mean by synchronization?

Currently, you can save your TreeSheets file in, say, DropBox, have it open on multiple computers, and any save will automatically reload the document on other computers (if they don't have unsaved changes, otherwise it will ask).

In case you are still reading: Mostly merging. If the file was edited offline at two points, merge these versions.

What happens in case of conflicts? I'm always interested to learn how applications deal with that

TreeSheets currently doesn't merge. If the file was modified in 2 locations without being saved first, the user has to choose which to keep. Not that this is mostly intended for single-users scenarios where typically a user edits on one computer at a time :)