The problem with putting the icon inside a "container" rather than add an outline, is that because of the musical note, the fact that the bee I designed is oval, and how the wing sticks out, the icon will always look like it's not properly centered.
There's something not quite right with this for example but the icon is centered.
However, an outline may
work for dark skins and I could again provide several versions depending on what you guys want.
I think I would make a separate icon to use inside MB because if you make the outline big enough so it's useful with the tiny icon inside MB, it's way too big when used in the Windows taskbar for example. See these below. Looks right on the large version but the smaller version would need a thicker outline.
I'm still not convinced about using an outline at all yet, but there's obviously something that needs to be done for darker skins.