private void ClickedMaterialSiteListButton(object sender, RoutedEventArgs e)
{
EditingMaterialSite win = new EditingMaterialSite();
win.Owner = GetWindow(this);
win.ShowDialog();
}
//以下イベント発生コード
//素材配布サイト追加クリック
private void MenuItem_Click(object sender, RoutedEventArgs e)
{
EditingMaterialSite win = new EditingMaterialSite();
win.Owner = GetWindow(this);
win.ShowDialog();
}