Hide title bar in Android 4.3 (Api 18) with xlabs

Hello,

In the Android part I am trying to hide the title bar.
For API 17, 19, 20, 21, 22 and 23 I have a theme with this item : <item name="android:actionBarSize">0dp</item>
For API 16, this does not work, so I created another theme which inherits from "android:Theme.Holo.NoActionBar"
This works as expected.

For API 18, (Android 4.3) neither of these two solutions work. And I always have a white bar on the top of the screen.
I have tried lot of things and I have 3 possible results :
- The white bar
- The action bar is not hidden
- An erreur at runtime (null pointe exception)

System.NullReferenceExceptionObject reference not set to an instance of an object
Raw
Xamarin.Forms.Platform.Android.MasterDetailRenderer.SetElement(VisualElement)
Xamarin.Forms.Platform.Android.RendererFactory.GetRenderer(VisualElement)
Xamarin.Forms.Platform.Android.Platform.AddChild(VisualElement, bool)
Xamarin.Forms.Platform.Android.Platform.SetPage(Page)
Xamarin.Forms.Platform.Android.FormsApplicationActivity.InternalSetPage(Page)
Xamarin.Forms.Platform.Android.FormsApplicationActivity.SetMainPage()
Xamarin.Forms.Platform.Android.FormsApplicationActivity.LoadApplication(Application)
DriversInfo.Droid.MainActivity.OnCreate(Bundle)
Android.App.Activity.n_OnCreate_Landroid_os_Bundle_(intptr, intptr, intptr)Android.App.Activity.cs:2741

I just noticed when copy/pasting the stack trace that my problem is related to Xlabs.
When I change my MainActivity from XFormsApplicationDroid to a regular Activity, my problem leave. It doesn't crash and the white bar is not displayed.

So, all these lines to ask : how to get rid of the white bar on Android 4.3 with Xlabs ?
Have anyone faced this issue ?

Thank you.