Code review comment for lp://qastaging/~fourdollars/unity-greeter/add-hidpi-support

Can't this just be completed using the existing GDK API instead of using X calls?

i.e.

var use_hidpi = false;
var screen = Gdk.Screen.get_default ()
for (var i = 0; i < screen.get_n_monitors (); i++)
{
    var width_mm = screen.get_monitor_width_mm (i);
    var height_mm = screen.get_monitor_height_mm (i);
    var ppi = ...
    if (ppp ...)
        use_hidpi = true;
}