WPF新的窗口返回值的方式

Yyqd_Window win = new Yyqd_Window()
{
CompanyID = textBox_companyId.Text.Trim(),
CompanyName = textBox_work_unit.Text.Trim(),
ImportName = ""
};
win.Unloaded += (o, ae) =>
{
if (win.SelectedValue != null)
{
this.Sign(win.SelectedValue);
}
};
DialogHelper.ShowDialog(win);
this.Focus();