new BrowserWindow([options])

type string (optional) - The type of window,
default is normal window.

The possible values and behaviors of the type
option are platform dependent.
Possible values are:

• On Linux, possible types are desktop, dock,
  toolbar, splash, notification.

The desktop type places the window at the desktop
background window level (kCGDesktopWindowLevel - 1).
Note that desktop window will not receive focus,
keyboard or mouse events, but you can use
globalShortcut to receive input sparingly.