Customized gradient editor

I want to use a gradient control in my editor script. But I want to it to work differently. I don’t want alpha keys to be separate from the color keys. I need alpha to be the part of colors.
Is there a way to do that?

I’ve seen some color editors which use a color wheel in order to show the RGB effects of a color radially (like the one from Paint.NET to choose primary and secondary colors):

137547-colorwheel.png

I would imagine that you could extrapolate that to a spherical color selector, where a portion of that sphere were the “alpha” channel, so it really wouldn’t look like a sphere, but kind of a semi-sphere where portions of it were missing (where the alpha values were completely transparent).

It’s a very interesting thought and sounds like a really cool way to choose colors not necessarily for gradients, but for their transparency as well.