Android actionbar gradient glitch

Question

My app actionbar has a gradient as background:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:startColor="@color/black"
        android:endColor="@android:color/transparent"
        android:angle="-90"/>
</shape>

It is applied to some activities programmatically using actionBar.setBackgroundDrawable(getResources().getDrawable(R.drawable.background_black_gradient));

The problem is that some times, when I run the app (even without changing the binary), the actionbar shows a dark contour (see image). It happens both in my Nexus 7 (2012) and in the emulator, and it seems to only happen with API 21.

Does any one else ever seen something like that? Does anyone know how to fix it?

Thanks!

Answer 1

It's the shadow of the Action Bar. You can remove it by using this line of code.

getSupportActionBar().setElevation(0);