Center palette window on screen?

Is there a way to have a palette display in the center of a users screen? Displaying a dialog like this does it just fine:

var w = new Window("dialog", "test", undefined);
w.show()

However, if I then simply change it to a palette..

var w = new Window("palette", "test", undefined);
w.show()

..it no longer displays in the center of the screen.

Does anyone know why this is?