gint gdk_screen_get_primary_monitor ( GdkScreen* screen )
Gets the primary monitor for
screen. The primary monitor
is considered the monitor where the “main desktop” lives.
While normal application windows typically allow the window
manager to place the windows, specialized desktop applications
such as panels should place themselves on the primary monitor.
If no primary monitor is configured by the user, the return value will be 0, defaulting to the first monitor.