SafeKeyboard/app/src/main/res/drawable/keyboard_number_selector_bg.xml

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

    <item android:state_pressed="false"
          android:state_checked="false"
          >
        <shape android:shape="rectangle">
            <corners  android:radius="4dp"/>
            <solid android:color="#474749"/>
        </shape>
    </item>

    <item android:state_pressed="true"
          android:state_checked="false"
         >
        <shape android:shape="rectangle">
            <corners  android:radius="4dp"/>
            <solid android:color="#1c69ac"/>
        </shape>
    </item>

</selector>