Comment 12 for bug 444548

When designing Notify OSD, we decided that mutedness should be orthogonal to volume -- that is, muted loudness should look different from muted quietness. This was so that you can get advance warning of how loud things are likely to be the moment you unmute.

In the volume applet we don't really have room to distinguish muted loudness from muted quietness, but we can still distinguish muted sound vs. zero volume. So, what Ara said. :-)