It is local view. I have several domains/projects under htdocs. To use PHP composer, I created httpdocs under each domain. It is working fine in the stable version.
You can’t select it of course, if it’s not empty.
If you want to use different folders for different projects like that, you’d need to create virtual hosts for them in your local wamp/mamp/xamp server.
Otherwise Wappler will always copy the files in your server root - the htdocs folder.