Allow The User To Enter Text Into The Combo Box To Type Entries Contained In The List Source?

am trying trying to write some code for a ComboBox that does the following:

1. Allow the user to enter text into the combo box to type entries contained in the list source.

2. Enable autocomplete to assist the user in selecting entries in the list source, both from dropped down state and non dropped down state.

3. Restrict the user from typing an entry that doesn't exist in the list source.

My requirements are:

1. The ComboBox must run some code after a selection has been made or the user has finished typing an entry (not after the focus has been moved to another control)

2. The code must only run once after the user has made a selection from the combobox or has finished typing an entry

The problem: To achieve the above functionality, I had to run code on numerous event's. Sureley there is a better way, here are the events and the reason for the code:

SelectedIndexChanged:This is the code that is run when the user makes a selection. No Mystery here

KeyDown:

Must Run
If e.KeyCode = Keys.Return Then
ComboBox1_SelectedIndexChanged(Nothing, Nothing)
End If