How do you use MeasureOverride in Silverlight?
protected override Size MeasureOverride(Size availableSize) {

    Size panelDesiredSize = new Size();


    if ((this.widthWrap) || (this.heightWrap))
    {

        foreach (UIElement elemento in this.Children)
        {

            System.Diagnostics.Debug.WriteLine(((FrameworkElement)elemento).DesiredSize.ToString());

            if (this.Orientation.Equals(System.Windows.Controls.Orientation.Vertical))
            {
                if (this.widthWrap)
                {
                    //the widest element will determine containers width
                    if (panelDesiredSize.Width < ((FrameworkElement)elemento).Width)
                        panelDesiredSize.Width = ((FrameworkElement)elemento).Width;
                }
                //the height of the Layout is determine by the sum of all the elment that it cointains
                if (this.heightWrap)
                    panelDesiredSize.Height += ((FrameworkElement)elemento).Height;
            }
            else
            {
                if (this.heightWrap)
                {
                    //The highest will determine the height of the Layout
                    if (panelDesiredSize.Height < ((FrameworkElement)elemento).Height)
                        panelDesiredSize.Height = ((FrameworkElement)elemento).Height;
                }

                //The width of the container is the sum of all the elements widths
                if (this.widthWrap)
                    panelDesiredSize.Width += ((FrameworkElement)elemento).Width;
            }

        }
    }

    System.Diagnostics.Debug.WriteLine("desiredsizzeeeeeee" + panelDesiredSize);

    return panelDesiredSize;

}