react-native-router-flux navBar navTransparent does't work well on android

Question

I am trying to set router-flux navBar transparent background, in IOS it works grate, in Android I have a very very thin white line in the bottom of the nav bar, looking like 3D/zIndex upper layer

Versions react-native-router-flux: "^4.0.0-beta.28" "react-native": "0.52.1",

Expected behaviour like in ios, completely transparent

Actual behaviour

Here is my code:

<Drawer key='DrawerRoot' contentComponent={SideMenu} drawerWidth={200}
       drawerImage={MenuIcon} drawerPosition='left' hideNavBar>
   <Scene key='scene1' component={comp1}
      drawer={true} navTransparent={true}/>
   <Scene key='scene2' component={comp2} title={'title'} back/>
</Drawer>

I would like to make it totally transparent. thanks to helpers