You can easily change the button-colors (iPad) of ButtonBars by applying
style:Titanium.UI.iPhone.SystemButtonStyle.BAR to it.
However when you do that for Buttons it adds an arrow-icon to the button and it doesn't look like it should. So how do I change a buttons color?
Fake it :)
Create a buttonBar with one label only, and set to this the backgroundColor.
For buttons, you would change the backgroundColor property in order to update the button color.