One way is to use events, such as
private void textBox_TextChanged(object sender, EventArgs e)
as the user types in the textbox have the event update the listbox.
Here is a hack I did for updating a datagridview from a textbox
private void textBox1_TextChanged(object sender, EventArgs e)
{
try
{
string sSearch = this.textBoxSearch.Text.Trim();
int iCnt = this.dataGridViewProductList.Rows.Count;
for (int i = 0; i < iCnt; i++)
{
if (0 < sSearch.Length)
{
DataGridViewCell cell1 = this.dataGridViewProductList[1, i];
string sCellval = Convert.ToString(cell1.Value);
while (sCellval.Length < sSearch.Length)
{
sCellval += "\x0020";
}
string text3 = sCellval.Substring(0, sSearch.Length);
if (string.Compare(sSearch, text3, true) == 0)
{
cell1.Selected = true;
i = iCnt;
}
}
}
}
catch
{
this.dataGridViewProductList.ClearSelection();
}
}