<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle"
    >
    <!-- This is the stroke you want to define -->
    <stroke android:width="2dp"
        android:color="@color/gray"/>

    <!-- Optional, round your corners -->
    <corners android:bottomLeftRadius="0dp"
        android:topLeftRadius="5dp"
        android:bottomRightRadius="5dp"
        android:topRightRadius="0dp" />

    <!-- Optional, fill the rest of your background with a color or gradient, use transparent if you only want the border to be displayed-->
    <gradient android:startColor="@android:color/transparent"
        android:endColor="@android:color/transparent"
        android:angle="90"/>
    <solid android:color="@color/background" />

</shape>