btn_simpale_normal.xml

<?xmlversion ="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item>
        <shape>
            <corners android:radius="25dp" />

            <gradient 
                android:startColor="#999999"
                android:angle="90"
                android:endColor="#E4E4E4"
                android:type="linear" />
        </shape>
    </item>
    <item
        android:bottom="3px"
        android:left="1px"
        android:right="2px"
        android:top="1px">
        <shape>
            <corners android:radius="25dp" />

            <gradient
                android:angle="90"
                android:endColor="#FFFFFF"
                android:startColor="#cccccc"
                android:type="linear" />
        </shape>
    </item>

    </layer-list>

btn_simpale_pressed.xml

<?xmlversion ="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item>
        <shape>
            <corners android:radius="25dp" />

            <gradient 
                android:startColor="#999999"
                android:angle="90"
                android:endColor="#E4E4E4"
                android:type="linear" />
        </shape>
    </item>
    <item
        android:bottom="1px"
        android:left="1px"
        android:right="1px"
        android:top="1px">
        <shape>
            <corners android:radius="25dp" />

            <gradient
                android:angle="90"
                android:endColor="#cccccc"
                android:startColor="#FFFFFF"
                android:type="linear" />
        </shape>
    </item>

    </layer-list>

select_button_simple.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:state_pressed="true" android:drawable="@drawable/btn_simpale_pressed"></item>
	<item android:drawable="@drawable/btn_simpale_normal"></item>
</selector>