Inset drawable not working as described in documentation

Try to use shape with left-padding instead of inset:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
    <solid android:color="@android:color/darker_gray"/>
    <padding android:left="100dp"/>
</shape>

By default, setting a background drawable also applies that drawable's padding to the view. Set the padding explicitly if you don't want it to match the background drawable.