The stock Android buttons you saw in the initial version of your app had a shadow effect. Unfortunately, shape drawables have no shadow property. But you can make the shadow effect yourself using two other XML drawable types: layer list drawables and inset drawables.
Here is how you will do it. First, you will create a shadow with the same shape as your current button drawable. Then you will combine it with the current button using
layer-list, and offset the bottom edge of the button a tad using
inset so that the shadow becomes visible underneath.
Create a new XML file in res/drawable/. Name it button_shape_shadowed.xml and make its root element
Listing 25.8 Normal button shadows (