Does Sigil/QT 5.1.0 support OTF font feature settings?
 

Some OpenType fonts, feature alternate stylistic sets that can be selected via additional CSS3 parameters.

I did some tests with embedded OTF fonts with alternate stylistic sets, but the font display didn't change in BookView mode. Am I right in assuming that QT 5.1.0 simply doesn't support -webkit-font-feature-settings/font-feature-settings?

And while we're at the topic, is there any Windows freeware font viewer (other than FontForge) that offers a preview option for these special OpenType-only font features?