protected override void OnSizeAllocated(Gdk.Rectangle allocation)
{
base.OnSizeAllocated(allocation);
// reduce allocation by border width
int bw = (int)BorderWidth;
allocation.X += bw;
allocation.Y += bw;
allocation.Width = Math.Max(1, allocation.Width - 2 * bw);
allocation.Height = Math.Max(1, allocation.Height - 2 * bw);
if (root != null && root.Visible)
{
root.SizeAllocate(allocation);
}
}