About the Full Screen And No Titlebar from manifest

To set your App or any individual activity display in Full Screen mode, insert the code

<application 
    android:icon="@drawable/icon" 
    android:label="@string/app_name" 
    android:theme="@android:style/Theme.NoTitleBar.Fullscreen">

in AndroidManifest.xml, under application or activity tab.

Another way: add windowNoTitle and windowFullscreen attributes directly to the theme (you can find styles.xml file in res/values/ directory):

<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowFullscreen">true</item>
</style>

in the manifest file, in application specify your theme

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

If your Manifest.xml has the default android:theme="@style/AppTheme"

Go to res/values/styles.xml and change

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">

to

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

And the ActionBar is disappeared!