Exclude from build is now in Project Structure-->sources tab. This let you specify a folder as being excluded from compiling. I would also like to see this ability as a choice on the the popup menu of th Project View. I find it convenient to take old classes and experiments and push them into a folder I call "old" which is directly under their original folder (directory). This lets me just sweep all that stuff which I am not yet ready to delete into a folder that is right at hand. Now that (one at a time only! ) drag and drop is in the Project View tree, this is one thing which can leverage that ability.