Ripple effect

Would be great if the background drawables had ripples for devices supporting it, else use the current background drawables as a fallback (no ripple, just a change in colour).

Start by locating the background drawable definitions and the code that selects them for different Android device versions. Confirm how ripple support is detected and identify the existing drawable fallback; done means supported devices show a ripple while other devices retain the current colour-change behavior.

Written by the indexing model from the issue text.