public ChooserDialog withOnBackPressedListener(OnBackPressedListener listener) {
        if (this._onBackPressed instanceof defBackPressed) {
            ((defBackPressed) this._onBackPressed)._onBackPressed = listener;
        }
        return this;
    }
called every time {@link KeyEvent#KEYCODE_BACK} is caught,
 and current directory is not the root of Primary/SdCard storage.
android-file-chooser/src/main/java/com/obsez/android/lib/filechooser/ChooserDialog.java