I just spent the better part of the morning searching Google, trying to figure out how to get a black fader in the Command Menu using Ares. I searched everywhere in Palm's documentation and their forums. The best solution I could find was the instruction on this forum post:

Add menuClass: 'no-fade' to your command menu attributes and that will remove the fade.

And that was to the same question I had. Talk about a non-solution! That was all I had: How do you change the command menu fade? You don't! After a few hours of searching, that was all I had, and it bothered me. Then I remembered that with Ares, webOS apps are running in a browser... *almost* any browser you choose. I fired up Safari, and after a few element inspections, I had the code necessary to change the command menu fader.

.palm-menu.command-menu.palm-dark > .palm-menu-fade {
background: url(../path/to/file.png) bottom left repeat-x;
}

And then, instead of changing menuClass to 'no-fade', I changed it to 'palm-dark' (menuClass: "palm-dark"). Of course, the class name does not have to be palm-dark, I just named it that because it fit.

All the mucking about the internet was not in vain. I also found an O'Reilly Quick Reference guide that listed the two official menuClass properties that work with Mojo out of the box: palm-default and palm-white. palm-default is the normal cream-colored fade, and palm-white is a white version (that, honestly, the Palm Facebook app should use instead of the cream one). I have example images of each below.