On Fedora 10, desktop-file-validate says that the diffuse desktop file is invalid as it doesn't conform to:
"Some keys can have multiple values. In such a case, the value of the key is specified as a plural: for example, string(s). The multiple values should be separated by a semicolon. Those keys which have several
values should have a semicolon as the trailing character."
With the addition of a trailing semi-colon on the lists of values, the file validates