@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK && hasVisibleDrawer()) {
            event.startTracking();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
Check if a given drawer view is currently visible on-screen. The drawer
may be only peeking onto the screen, fully extended, or anywhere in between.
If there is no drawer with the given gravity this method will return false.

@param drawerGravity Gravity of the drawer to check
@return true if the given drawer is visible on-screen
app/src/main/java/com/sunnyweather/android/ui/customerUIs/HomeDrawerLayout.java