C# Extension Method - Build and show exception message

public static void ShowError(this Exception exception)
{
    MessageBox.Show(exception.GetType().ToString() + " occured:\n" + BuildErrorMessage(exception), Assembly.GetEntryAssembly().GetName().Name, MessageBoxButtons.OK, MessageBoxIcon.Error);
}
public static string BuildErrorMessage(Exception ex)
{
    string s = string.Empty;
    s += ex.Message + ex.StackTrace;
    if (ex.InnerException != null)
    {
        s += BuildErrorMessage(ex.InnerException);
    }
    return s;
}