http://docs.appcelerator.com/platform/latest/#!/guide/Android_Themes-section-34636181_AndroidThemes-CustomThemes

mytheme.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <style name="Light" parent="Theme.AppCompat.Light"/>
    <style name="Dark" parent="Theme.AppCompat"/>
    <style name="Theme.CustomActionBar" parent="@style/Theme.AppCompat.Light">
        <!-- Specify an Action Bar style to use --> 
    </style>
 
</resources>

tiapp.xml

............
<android xmlns:android="http://schemas.android.com/apk/res/android">
        <manifest android:versionCode="1" android:versionName="1.0"
            package="mobi.wapZone" xmlns:android="http://schemas.android.com/apk/res/android">
            <uses-sdk android:minSdkVersion="14" android:targetSdkVersion="23"/>
            <application android:debuggable="false"
                android:icon="@drawable/appicon" android:label="wapZone"
                android:name="WapzoneApplication" android:theme="@style/Theme.CustomActionBar">
                <activity
                    android:configChanges="keyboardHidden|orientation|screenSize"
                    android:label="@string/app_name"
                    android:name=".WapzoneActivity"
                    android:screenOrientation="nosensor" android:theme="@style/Theme.CustomActionBar">
                    <intent-filter>
                        <action android:name="android.intent.action.MAIN"/>
                        <category android:name="android.intent.category.LAUNCHER"/>
                    </intent-filter>
                </activity>
                 
            </application>
        </manifest>
    </android>
    
    ............