I open a file, I edit it. After I began editing, the file is modified by another program. Finally, I save the file.
In that case, Vim would provide that helpful warning:
WARNING: The file has been changed since reading it
Do you really want to write to it (y/n)?
But Textmate will overwrite the file silently, which can result in unpleasant data loss (in my case, a de facto revert on Git). How can I prevent that?