Listbox On ClickFires Too Much. . .

[Stubble]

I have code that selects records in a listbox called [By Search Type]
based on the value typed in a textbox called txtVendor like the
windows help that narrows the possiblities as the user types.

One of the specifications is that the first possible record should be
selected.

It worked fine until the client decided that when they single click on
the listbox, they want that value that they just clicked on to be sent
to populate the textbox.

So I put code into the On Click event that does just that.

But now, when the user types one letter, the listbox is requeried and
the first available record is selected (as it is supposed to) but the
On Click unceremoniously fires when it receives the focus incrrectly
populating the textbox making it very difficult to type!

1) Why is the On Click firing when there was no click?

2) I've tried shifting the code into different events but to no avail.
Is there a way that the On Click will only fire when it's clicked!?!

My code follows:
*************** *************** *************** ***********
Private Sub txtVendor_Chang e()

RefreshVendorLi st

Me.[By Search Type].SetFocus
Me.[By Search Type].Selected(0) = True

DoCmd.GoToContr ol "txtVendor"
Me.txtVendor.Se tFocus
If Not IsNull(Me.txtVe ndor) Then
Me.txtVendor.Se lStart = Len(Me.txtVendo r)
End If

End Sub
*************** *************** *************** ************
Function RefreshVendorLi st()
Me.[By Search Type].SetFocus

Me.[By Search Type].RowSource = "SELECT Vendor.[Vendor Code],
Vendor.Name" _
& " FROM Vendor WHERE Vendor.[Vendor Code] Like '" &
[Forms]![VendorSearch]![txtVendor] & "*'" _
& " ORDER BY Vendor.[Vendor Code];"

Me.[By Search Type].Requery

End Function
*************** *************** *************** ************
Private Sub By_Search_Type_ Click()
Me.txtVendor = Trim(Me.[By Search Type].Column(0))
End Sub