Vim is most famous for the steep learning curve, and only a little less famous for how useful it is. Today, mucking about with xlm files in MacVim I discovered a nice validation trick.
With the bar.xml open, you can easily validate against foo.xsd. First, save your changes and then hit `:` and enter the following (it’s the pipe to the terminal command).
:! xmllint --noout --schema foo.xsd bar.xml