* Electron Version: 3.0.0-beta1
* Operating System (Platform and Version): macOS
* Last known working Electron version: 2.0.2

**Expected Behavior**
```css
html, body, * {
    -webkit-app-region: drag;
    -webkit-user-select: none;
    cursor: default;
}
```
should allow users to move the position of the window by dragging it directly.

**Actual behavior**
The window is not draggable.
The `cursor` and `-webkit-user-select` properties work well.

**To Reproduce**
copy the CSS above, paste it into a frameless app's `<style>` tag, and run the app.

**Screenshots**

**Additional Information**

atom/browser/api/atom_api_browser_window.h
void RenderViewHostChanged(content::RenderViewHost* old_host,
                             content::RenderViewHost* new_host) override;
  void RenderViewCreated(content::RenderViewHost* render_view_host) override;
  void DidFirstVisuallyNonEmptyPaint() override;
  void BeforeUnloadDialogCancelled() override;
  void OnRendererUnresponsive(content::RenderProcessHost*) override;
  bool OnMessageReceived(const IPC::Message& message,
                         content::RenderFrameHost* rfh) override;
  
  void OnCloseContents() override;
  void OnRendererResponsive() override;
  
  void RequestPreferredWidth(int* width) override;
  void OnCloseButtonClicked(bool* prevent_default) override;
  
  void OnWindowClosed() override;
  void OnWindowBlur() override;
  void OnWindowFocus() override;
  void OnWindowResize() override;
  void OnWindowLeaveFullScreen() override;
  void Focus() override;
  void Blur() override;
  void SetBackgroundColor(const std::string& color_name) override;
  void SetBrowserView(v8::Local<v8::Value> value) override;
  void SetVibrancy(mate::Arguments* args) override;
  
  void FocusOnWebView();
  void BlurWebView();
  bool IsWebViewFocused();