In 1.4.5, Electron added a new API (`previewFile`) that allows you to open a quicklook preview panel. However, there isn't an API for closing the preview panel that is opened.

QLPreviewPanel is a subclass of NSWindow - using Mac OS X APIs, it's pretty easy to close the shared Quicklook preview panel.

We need this functionality because the panel does not close automatically when the window is blurred, or when another window is opened in the application (https://github.com/nylas/N1/issues/3021). Other user action, such as moving focus to a message that doesn't have quicklook attachments should also probably close the panel.

I'm not sure what a good name for this API would be. Maybe `dismissFilePreview` or `unpreviewFile`? 
atom/browser/native_window.h
}
namespace content {
struct NativeWebKeyboardEvent;
}
namespace gfx {
class Point;
class Rect;
class Size;
}
namespace mate {
class Dictionary;
}
namespace atom {
struct DraggableRegion;
class NativeWindow : public base::SupportsUserData,
                     public content::WebContentsObserver {
 public:
  ~NativeWindow() override;
  
  
  static NativeWindow* Create(
      brightray::InspectableWebContents* inspectable_web_contents,
      const mate::Dictionary& options,
      NativeWindow* parent = nullptr);
  
  static NativeWindow* FromWebContents(content::WebContents* web_contents);
  void InitFromOptions(const mate::Dictionary& options);
  virtual void Close() = 0;
  virtual void CloseImmediately() = 0;
  virtual bool IsClosed() const { return is_closed_; }