And for your additional pleasure, I just checked into trunk code that shows what alternative glyphs are available from the OpenType tables: 'salt', 'ss01', 'ss02', ...
Expand the "Feature Settings" section of the "Variants" tab of the "Text and Font" dialog to see them.
I realize the GUI is less than ideal, but at least you can now see the available glyphs.
And for your additional pleasure, I just checked into trunk code that shows what alternative glyphs are available from the OpenType tables: 'salt', 'ss01', 'ss02', ...
Expand the "Feature Settings" section of the "Variants" tab of the "Text and Font" dialog to see them.
I realize the GUI is less than ideal, but at least you can now see the available glyphs.