In Activity.dispatchTrackballEvent() return true.
But this is not the way you should handle it, because it will ruin the experience on non touch screen devices. You should make your own theme with another color for the selected items.
Though, I am very much against using different themes for applications, and every developer, who is developing to sell their apps publicly should too! Because a platform should deliver a consistent look-and-feel across the whole system. If you go around and make for every app you develop a different theme, then every app looks different and that can and will be unsettling for not so tech savvy users!
Btw: you are very much allowed to dislike the selection color, but you are not the boss of your users' phones (of course, unless, you are their boss and your app only needs to be on their phone
). So people should be able to make their own decisions about the theme of their phone and apps on it, when every developer starts using their own custom theme then users can't choose their own theme, because your fixed your theme upon them.