Use the Button Magic Render Options dialog to modify the options used when a button is rendered for display.
Find it: Choose Edit > Render Options in the main Button Magic window.
The Render Options dialog contains the following items:
Note: Because GIF only supports 1 bit alpha, it is recommended that you set the shadow fringe to 0 and the opacity to 0.50; this produces the most visually pleasing shadow dithering pattern. But by all means experiment!