XML file saved at res/drawable/gradient_box.xml:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:startColor="#FFFF0000"
        android:endColor="#80FF00FF"
        android:angle="45"/>
    <padding android:left="7dp"
        android:top="7dp"
        android:right="7dp"
        android:bottom="7dp" />
    <corners android:radius="8dp" />
</shape>
(The above shape definition is is taken from then Android developer guide. There's no errors in it.).
Let's try to use it together with a TextView:
<TextView 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Text with some crazy rectangle shape below it."
    android:drawableBottom="@drawable/gradient_box"/>   
The TextView displays as if the drawableBottom attribute wasn't there! However, setting the shape as the background works just fine:
<TextView 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:text="Text with crazy background"
    android:background="@drawable/gradient_box"/>
Setting an actual image (e.g. a *.png) to the android:drawableBottom also works fine.
Any ideas?