private void button1_Click(object sender, EventArgs e)
        {
            var add = new Suggestion_for_improvement()
            {
                Suggestion = new Suggestion_for_improvements()
            };

            if (add.ShowDialog(this) == DialogResult.OK)
            {
                listBox1.Items.Add(add.Suggestion);
            }
        }
        private void listBox1_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            int index = this.listBox1.IndexFromPoint(e.Location);

            if (index != ListBox.NoMatches)
            {
                var item = (Suggestion_for_improvements)listBox1.Items[index];
                var add  = new Suggestion_for_improvement()
                {
                    Suggestion = item
                };
                if (add.ShowDialog(this) == DialogResult.OK)
                {
                    listBox1.Items.Remove(item);
                    listBox1.Items.Insert(index, item);
                }
            }
        }