[TIMOB-1368] tabview back button background image shrinks

The tabview back button on top left, when i set its background image. it shrinks it so it shows up in the middle.

Image size is 97 x 31 png

function open_property_detail(oid)
{   var property_detail_win = Titanium.UI.createWindow({
        titlePrompt: ' ',
        barImage: 'images/title_bg.png',    
        backgroundColor:'#000000',
        backButtonTitleImage: 'images/back_btn.png',
        url:'view.js'
        //orientationModes: [Titanium.UI.PORTRAIT, Titanium.UI.LANDSCAPE_RIGHT, Titanium.UI.LANDSCAPE_LEFT]
    });
    property_detail_win.oid = oid;
    Titanium.UI.currentTab.open(property_detail_win,{animated:true});
}