Right now only replacing the icon in the action bar is supported.
That's why the term "Icon Pack" is used in the UI.
Known bug: In a PreferenceActivity the second level still shows the
default app icon in the action bar :(
Icon packs need to include an activity with an intent filter for
the action "org.k9mail.THEME_PACK".
Example:
<activity android:name=".SomeActivity">
<intent-filter>
<action android:name="org.k9mail.THEME_PACK" />
</intent-filter>
<!-- Version number for the theme pack format -->
<meta-data android:name="version" android:value="1"/>
<meta-data android:name="name" android:value="Fancy icon"/>
<meta-data android:name="author" android:value="cketti"/>
<meta-data android:name="icon_app"
android:resource="@drawable/ic_app"/>
</activity>