private void katalogasToolStripMenuItem_Click(object sender, EventArgs e)
        {
            this.Hide();
            Katalogas newForm = new Katalogas();

            newForm.ShowDialog();
            this.Close();
        }
        private void back_Click(object sender, EventArgs e)
        {
            this.Hide();
            Katalogas newForm = new Katalogas();

            newForm.ShowDialog();
            this.Close();
        }
        private void buttonFilter_Click(object sender, EventArgs e)
        {
            string target = comboBoxFilter.SelectedItem.ToString();
            string item   = textBoxFilter.Text;

            this.Hide();
            Katalogas newForm = new Katalogas(1, target, item);

            newForm.ShowDialog();
            this.Close();
        }