- Electron version: `0.37.4`
- Operating system: Windows

When I maximize my [frameless](https://github.com/electron/electron/blob/master/docs/api/frameless-window.md) electron window a small part of the window in an unmaximized state is visible on a secondary monitor.

**Screenshot**
![electronbug](https://cloud.githubusercontent.com/assets/6634592/14762341/8849c728-09bb-11e6-85d8-de12db3fee2d.PNG)

You can visibly see the "line between the monitors" and you can see some really strange overhanging content that is over that line.

**Steps to reproduce**  
1. Open an electron app
2. Maximize the app on your secondary display
3. Look closely for the overflow onto your primary display

This might take a few times to trigger, it appears to do it about 70% of the time :confused: 

atom/browser/native_window_views.cc
content::WebContents*,
    const content::NativeWebKeyboardEvent& event) {
  keyboard_event_handler_->HandleKeyboardEvent(event, GetFocusManager());
  if (!menu_bar_)
    return;
  
  if (menu_bar_visible_ && IsAltKey(event))
    menu_bar_->SetAcceleratorVisibility(
        event.type == blink::WebInputEvent::RawKeyDown);
  
  if (event.type == blink::WebInputEvent::RawKeyDown && !IsAltKey(event) &&
      IsAltModifier(event)) {
    if (!menu_bar_visible_ &&
        (menu_bar_->GetAcceleratorIndex(event.windowsKeyCode) != -1))
      SetMenuBarVisibility(true);
    menu_bar_->ActivateAccelerator(event.windowsKeyCode);
    return;
  }
  if (!menu_bar_autohide_)
    return;
  
  if (event.type == blink::WebInputEvent::RawKeyDown && IsAltKey(event)) {
    
    menu_bar_alt_pressed_ = true;
  } else if (event.type == blink::WebInputEvent::KeyUp && IsAltKey(event) &&
             menu_bar_alt_pressed_) {