I don&#x27;t know how dropbox has actually implemented this, and I&#x27;m not sure about OSX,
But on windows you might use a kernel file system filter driver or a shell namespace extension:
<a href="https:&#x2F;&#x2F;msdn.microsoft.com&#x2F;en-us&#x2F;library&#x2F;windows&#x2F;desktop&#x2F;cc144095(v=vs.85).aspx" rel="nofollow">https:&#x2F;&#x2F;msdn.microsoft.com&#x2F;en-us&#x2F;library&#x2F;windows&#x2F;desktop&#x2F;cc1...</a><p>This looks like an open source project that provides something similar for google drive:
<a href="https:&#x2F;&#x2F;github.com&#x2F;google&#x2F;google-drive-shell-extension" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;google&#x2F;google-drive-shell-extension</a><p>On linux this could probably be even easier, just mounting a directory to a remote NFS server.