public static Drawable getSelectableBackground(Context ctx) {
        int selectableBackgroundRes = getSelectableBackgroundRes(ctx);
        return ContextCompat.getDrawable(ctx, selectableBackgroundRes);
    }
public static Drawable getSelectableBackground ( Context ctx ) { int selectableBackgroundRes = getSelectableBackgroundRes ( ctx ) ; return ContextCompat . getDrawable ( ctx , selectableBackgroundRes ) ; }
helper to get the system default selectable background

@param ctx
@return