* Output of `node_modules/.bin/electron --version`: 2.0.0
* Operating System (Platform and Version): Windows 10

**Expected Behavior**
When I disable a window twice via `setEnabled(false)`, I expect the second disable to have no effect.

**Actual behavior**
The second disable is "queued" up, such that I am forced to enable the window twice to get back to normal.

**To Reproduce**
In the electronquickstart repo, in main.js' `createWindow()`, add these lines:

    mainWindow.setEnabled(false);
    mainWindow.setEnabled(false);
    mainWindow.setEnabled(true);

The window will be disabled when launched. 

You see the same issue if you do it in reverse:

    mainWindow.setEnabled(true);
    mainWindow.setEnabled(false); // this doesn't actually disable it, because the window was enabled from the getgo

If this is expected behavior, can the [docs](https://github.com/electron/electron/blob/master/docs/api/browser-window.md#winsetenabledenable) be updated to explain this behavior.
atom/browser/native_window_views.cc
#if defined(USE_X11)
  if (menu_model == nullptr)
    global_menu_bar_.reset();
  if (!global_menu_bar_ && ShouldUseGlobalMenuBar())
    global_menu_bar_.reset(new GlobalMenuBarX11(this));
  
  if (global_menu_bar_ && global_menu_bar_->IsServerStarted()) {
    global_menu_bar_->SetMenu(menu_model);
    return;
  }
#endif
  
  gfx::Size content_size = GetContentSize();
  bool should_reset_size = use_content_size_ && has_frame() &&
                           !IsMenuBarAutoHide() &&
                           ((!!menu_model) != root_view_->HasMenu());
  root_view_->SetMenu(menu_model);
  if (should_reset_size) {
    
    int menu_bar_height = root_view_->GetMenuBarHeight();
    extensions::SizeConstraints constraints = GetContentSizeConstraints();
    if (constraints.HasMinimumSize()) {
      gfx::Size min_size = constraints.GetMinimumSize();
      min_size.set_height(min_size.height() + menu_bar_height);