This doesn't accomplish precisely what you want, but it sure simplified my life. I made a diagram with all the box styles I use (I use the same color combos/font/borders/padding over and over) and saved that diagram as my default. So instead of creating a new diagram every time, I open this one and immediately save it with the name I intend to use. I have versions of all my boxes ready, and they have all the attributes I need.
Thanks-
Jim Clark