Is there any solution to hide the bar where are Back Button,Home Button etc... ?

Hello,

First, I'm sorry for my english which could be not really good.

I'm developing an App on an Android (4.1.1) tablet which doesn't have hardware back button, home button etc... but there are on the screen, in a bar. I've already developed an other back button inside the app which have the same behavior like the native one. Now I would like to hide this bar when the app is running.

I'm using 3.1.3.GA Titanium SDK. I've already tried to put fullscreen:true property on my window. I've also changed my tiapp.xml putting

<statusbar-hidden>true</statusbar-hidden>
<fullscreen>true</fullscreen>
<navbar-hidden>true</navbar-hidden>

Thanks for your help.