Mobile Web: Change Tabs Height = black screen (bug? )

Hello,

I have been trying to change the height of tab on mobile web for a while now. The tabs are just too large for a mobile browser. As soon as I change the height property I get a black screen for the tab window and the app is not usable:

var tabGroup = Ti.UI.createTabGroup({
    tabsBackgroundColor :theme.buttonColor,
    tabsBackgroundSelectedColor : theme.backgroundColorDark,
    id : 'tabGroup1',
    //height : 40,   <-- causes the tabs to float the middle of screen and the tab window all black
    //bottom:0  <-- pushes the tab to the bottom. But the screen is still black
 
});
Titanium.UI.currentTabGroup = self;

Thanks!