Gradients

Another thing missing from CSS which is present in Metacity v2 themes is the ability to draw gradients.  In Metacity v2, a gradient can be

• any one of vertical, horizontal or diagonal
• between two or more colours, which can be specified as any colour format Metacity supports

How should we best represent this in Cowbell themes?

Option A:

frame {
background-image: -cowbell-gradient (diagonal, green, blue);
}

Option B:

frame {
background-image: url(“wm:gradient,diagonal,green,blue”);
}

Option C:

frame {
background-image: -cowbell-gradient();
-cowbell-gradient-direction: diagonal;
-cowbell-gradient-color: green blue;
}

Option D:

frame {
background-color: -cowbell-gradient(diagonal, blue, green);
}

Or some combination of these.  Or perhaps you can think of a better way.