Gradient of n colors ranging from color 1 and color 2
colorRampPalette could be your friend here: And just to show it works:
gradient
Android LinearLayout Gradient Background
Ok I have managed to solve this using a selector. See code below: main_header.xml: main_header_selector.xml: Hopefully this helps someone who has the same problem.
Gradient borders
WebKit now (and Chrome 12 at least) supports gradients as border image: Prooflink — http://www.webkit.org/blog/1424/css3-gradients/Browser support: http://caniuse.com/#search=border-image