private void button_Copy_Click(object sender, RoutedEventArgs e)
{
List <Material> list = new MaterialBLL().Search(txPesquisa.Text);
list.ForEach(mat =>
{
if (MaterialEntrada.Count(m => m.Id == mat.Id) == 0)
{
MaterialEntrada.Add(mat);
}
});
listMateriaisEntradas.Items.Refresh();
}