code:

// Nasty hack to make the grid spacing uniform in both axes
// I get the hit rect of two horizontally contiguous 
// elements and compare the distance between them in X
ButtonGridView.ChildViewAdded += (object sender, ViewGroup.ChildViewAddedEventArgs e) => {
	if (ButtonGridView.ChildCount == ButtonData.Count)
	{
		Android.Graphics.Rect hitrect_a, hitrect_b;
		hitrect_a = new Android.Graphics.Rect ();
		hitrect_b = new Android.Graphics.Rect ();
		ButtonGridView.GetChildAt(0).GetHitRect (hitrect_a);
		ButtonGridView.GetChildAt(1).GetHitRect (hitrect_b);
		int horizontal_distance = hitrect_b.Left - hitrect_a.Right;
		ButtonGridView.SetVerticalSpacing(horizontal_distance);
	}
};