Bug 42443: Shrink window to match letterboxing size when the emtpy area is clicked.

    return false;

  }

  _onWindowDoubleClick(e) {

    if (e.target.classList.contains("browserStack")) {

      e.currentTarget.shrinkToLetterbox();

    }

  }

  _attachWindow(aWindow) {

    aWindow.addEventListener("sizemodechange", windowResizeHandler);

    aWindow.shrinkToLetterbox = this.shrinkToLetterbox;

    aWindow.addEventListener("dblclick", this._onWindowDoubleClick);

    aWindow.gBrowser.addTabsProgressListener(this);

    aWindow.addEventListener("TabOpen", this);

    const resizeObserver = (aWindow._rfpResizeObserver =

      let browser = tab.linkedBrowser;

      this._resetContentSize(browser);

    }

    aWindow.removeEventListener("dblclick", this._onWindowDoubleClick);

    delete aWindow.shrinkToLetterbox;

    aWindow.removeEventListener("sizemodechange", windowResizeHandler);

  }