Add .dropboxignore directory to exclude folders without using selective sync

There are many scenarios in which an application adds little hidden files to a folder, which should be considered local metadata and not synced to other computers.

For example:

• folder thumbnail database (added by some file managers)
• folder view settings file (added by some file managers)
• lock files (temporarily added by some software like RStudio)
• ...

Instead of providing a general solution to this problem, Dropbox currently hard-codes a small selection of such filenames to exclude from syncing:

• desktop.ini
• thumbs.db
• .ds_store
• icon\r
• .dropbox
• .dropbox.attr

This covers the metadata files added by the default file managers on Windows and Mac and by Dropbox itself, but not those added by other kinds of programs like RStudio and by third-party or Linux file managers.

Please provide a more general solution!

Other file syncing software has supported this for ages: For example, git allows users to specify a custom list of filenames to exclude in .gitignore.

If adding such a feature to the Dropbox UI is too much work, then make it so that we e.g. manually have to edit the .dropbox file to specify what filenames to exclude. That's fine. But please do add this feature one way or another!