How to remove button shadow (android)
Another alternative is to add
style="?android:attr/borderlessButtonStyle"to your Button xml as documented here http://developer.android.com/guide/topics/ui/controls/button.html
An example would be
<Buttonandroid:id="@+id/button_send"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/button_send"android:onClick="sendMessage"style="?android:attr/borderlessButtonStyle" />