How can I have a drop shadow on my ActionBar (ActionBarSherlock)?

Question

I am including my styled xml layout:

Using @null value removes the shadow.

This one line sets the shadow on ActionBar on Android 3.0 and newer. However if you are using ActionBarSherlock, it will not work as you expect. It would create the shadow on top of the window over the ActionBarSherlock on Android devices running system older than Android 4.0 (although ActionBar is present in the api since Android 3.0, ActionBarSherlock uses custom implementation for all Android versions older than Android 4.0).

To create the shadow below ActionBarSherlock you have to set windowContentOverlay parameter on the application theme (notice the missing android:).

Again, using @null removes the shadow.

Although this line works for ActionBarSherlock, it doesn't work on android devices running Android 4.0 and newer, no shadow is created under the ActionBar on such devices. So how to combine these two parameters to get the desired shadow under both ActionBar and ActionBarSherlock?

Use resource configuration qualifiers, in your case use platform version qualifiers. In res/values/styles.xml use the second xml code. And in res/values-v14/styles.xml use the first xml code. Therefore the ActionBarSherlock version is used by default (for versions pre Android 4.0) and ActionBar version is used for Android 4.0 and newer.

Edit: There is a bug in Android 4.3 (API level 18), android:windowContentOverlay does not work. It should be fixed in future release. In case you need it fixed in Android 4.3, you can find workarounds linked in the bug report.