On 7 Mar 2021, at 20:10, Quinn Comendant via TextMate wrote:

This behavior would be explained if untitled windows have a default Project Folder of ~/src/ (without showing this in the window's title area). If that's true, the question is: how to unset the Project Folder for untitled windows?

The default is the setting of Preferencs → Projects → File browser location.

So in your case, you should set this to a folder in which there are no files (even in sub-folders) that you would normally open with mate.

For me, when I open a new untitled window, it does show this location in the window title. Perhaps you have set windowTitle somewhere? You can check this with Bundles → Select Bundle Item… switch to Settings (⌘}) and then enter windowTitle.

As for why untitled windows have a default project folder: Internally there is no distinction, i.e. each window is a project, it can have the file browser shown or hidden, and it can have one or more tabs, either of them being “untitled”.

Though the behavior you experienced is unexpected, so I will reconsider if there should be exceptions.