cursos-android/vitamio/res/drawable/mediacontroller_button.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:drawable="@color/mediacontroller_bg_pressed" android:state_focused="true"/>
    <item android:drawable="@color/mediacontroller_bg_pressed" android:state_pressed="true"/>
    <item android:drawable="@color/transparent" android:state_enabled="false"/>
    <item android:drawable="@color/transparent"/>


</selector>