private void zapiszToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                richTextBox1.SaveFile(saveFileDialog1.FileName, RichTextBoxStreamType.PlainText);
            }
        }

        private void wczytajToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                richTextBox1.LoadFile(openFileDialog1.FileName, RichTextBoxStreamType.PlainText);
            }