* 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 (is_modal())
      state_atom_list.push_back(GetAtom("_NET_WM_STATE_MODAL"));
  }
  if (!state_atom_list.empty())
    ui::SetAtomArrayProperty(GetAcceleratedWidget(), "_NET_WM_STATE", "ATOM",
                             state_atom_list);
  
  if (!window_type.empty())
    SetWindowType(GetAcceleratedWidget(), window_type);
#endif
#if defined(OS_WIN)
  if (!has_frame()) {
    
    
    DWORD frame_style = WS_CAPTION;
    if (resizable_)
      frame_style |= WS_THICKFRAME;
    if (minimizable_)
      frame_style |= WS_MINIMIZEBOX;
    if (maximizable_)
      frame_style |= WS_MAXIMIZEBOX;
    
    if (!thick_frame_)
      frame_style &= ~(WS_THICKFRAME | WS_CAPTION);
    ::SetWindowLong(GetAcceleratedWidget(), GWL_STYLE, frame_style);
  }
  LONG ex_style = ::GetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE);
  if (window_type == "toolbar")
    ex_style |= WS_EX_TOOLWINDOW;
  ::SetWindowLong(GetAcceleratedWidget(), GWL_EXSTYLE, ex_style);