The docs state "All files passed on the command line will be opened. If Sublime Text is already running, then the files will be opened by the existing instance, rather than a new one being started."
This does not happen with Sublime 2 on Windows. It opens a new window with a project containing only the new directory.
If sublime is not running, it opens and adds the directory to the existing project. This is the preferred behavior and should happen even if sublime (subl) is already running.
Ideally there should be a command line utility like there is on osx that allows for control of this.
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