protected override void OnGetPreferredWidth(out int minimum_width, out int natural_width)
{
int min1, width1, min2, width2, sw = Handler.SplitterWidth;
Child1.GetPreferredWidth(out min1, out width1);
Child2.GetPreferredWidth(out min2, out width2);
minimum_width = Handler.GetPreferredPanelSize(min1, min2);
natural_width = Handler.GetPreferredPanelSize(width1, width2);
}