Issue with combobox autocomplete - vb.net

Question

I am trying to incorporate three comboboxes into a functional GUI which consist of textboxes, numericupdown controls and now comboboxes.
On those form I have navigation with keyboard (me.selectnextcontrol) with keys up and down.
What happens?
When I step in those GUI for first time everything work OK and I can move up/down with keyboard as expected.
Problem becomes when I edit a combobox which is in the midle of my gui and is set like this:
mycombo.AutoCompleteMode = AutoCompleteMode.SuggestAppend
mycombo.AutoCompleteSource = AutoCompleteSource.CustomSource
mycombo.AutoCompleteCustomSource = myAutoCompleteStringCollection
Problem is that when I come back to those combobox my navigation loop don't get keypress (up or down keys) anymore because combobox takes them for itselfs purpose (change index).
I try with mycombo.AutoCompleteSource = AutoCompleteSource.CustomSource after combobox_Leave but that turns off autocomplete what is not wanted.
Question is:
Is here possible to set described combobox after usage in mode like it was at the beginning of program, when it was not edited, so I can navigate with keyboard through such comboboxes at initial way but that autosuggest option remain enabled if I need to edit it again.
EDITED:
Here is simple example which shows a problem:
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim tb As New TextBox
Dim cbb As New ComboBox
Dim tbb As New TextBox
Dim b1 As New Button
Dim b2 As New Button
With Me
.KeyPreview = True
.Size = New Size(350, 200)
With .Controls
.Add(tb)
With tb
.TabIndex = 0
.Location = New Point(95, 20)
.Text = "This is"
End With
.Add(cbb)
With cbb
.TabIndex = 1
.Items.AddRange(New String() {"alabama", "africa", "australia", "grenland"})
.Location = New Point(95, 50)
.Text = "an Example"
.DropDownStyle = ComboBoxStyle.DropDown
.AutoCompleteMode = AutoCompleteMode.SuggestAppend
.AutoCompleteSource = AutoCompleteSource.ListItems
End With
.Add(tbb)
With tbb
.TabIndex = 2
.Location = New Point(95, 80)
.Text = "textbox"
End With
.Add(b1)
With b1
.TabStop = False
.Location = New Point(90, 130)
.Text = "Nothing"
End With
.Add(b2)
With b2
.TabStop = False
.Location = New Point(170, 130)
.Text = "Exit"
AddHandler b2.Click, AddressOf b2_Click
End With
End With
End With
End Sub
Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown
If e.KeyCode = Keys.Up Then
e.Handled = True
Me.SelectNextControl(Me.ActiveControl, False, True, True, True)
End If
If e.KeyCode = Keys.Down Then
e.Handled = True
Me.SelectNextControl(Me.ActiveControl, True, True, True, True)
End If
End Sub
Private Sub b2_Click(ByVal sender As Object, ByVal e As System.EventArgs)
Me.Close()
End Sub
End Class
When you start this program pass several times through all controls with key down arrow. Then stop on combobox and type letter "a", then try to navigate again with key down arrow.

Answer 1

Public Class Form1
Private tb As New TextBox
Private cbb As New ComboBox
Private tbb As New TextBox
Private b1 As New Button
Private b2 As New Button
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
AddHandler cbb.PreviewKeyDown, AddressOf cbb_PreviewKeyDown
AddHandler tb.PreviewKeyDown, AddressOf tb_PreviewKeyDown
AddHandler tbb.PreviewKeyDown, AddressOf tbb_PreviewKeyDown
Me.Size = New Size(350, 200)
With tb
.Parent = Me
.TabIndex = 0
.Location = New Point(95, 20)
.Text = "This is"
End With
With cbb
.Parent = Me
.TabIndex = 1
.Items.AddRange(New String() {"alabama", "africa", "australia", "grenland"})
.Location = New Point(95, 50)
.Text = "an Example"
.DropDownStyle = ComboBoxStyle.DropDown
.AutoCompleteMode = AutoCompleteMode.SuggestAppend
.AutoCompleteSource = AutoCompleteSource.ListItems
End With
With tbb
.Parent = Me
.TabIndex = 2
.Location = New Point(95, 80)
.Text = "textbox"
End With
With b1
.Parent = Me
.TabStop = False
.Location = New Point(90, 130)
.Text = "Nothing"
End With
With b2
.Parent = Me
.TabStop = False
.Location = New Point(170, 130)
.Text = "Exit"
AddHandler b2.Click, AddressOf b2_Click
End With
End Sub
Private Sub tb_PreviewKeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.PreviewKeyDownEventArgs)
If e.KeyCode = Keys.Up Then tbb.Focus()
If e.KeyCode = Keys.Down Then cbb.Focus()
End Sub
Private Sub cbb_PreviewKeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.PreviewKeyDownEventArgs)
If e.KeyCode = Keys.Up Then
cbb.AutoCompleteMode = AutoCompleteMode.None
tb.Focus()
cbb.AutoCompleteMode = AutoCompleteMode.SuggestAppend
If Not cbb.Items.Contains(cbb.Text) Then cbb.Text = ""
End If
If e.KeyCode = Keys.Down Then
cbb.AutoCompleteMode = AutoCompleteMode.None
tbb.Focus()
cbb.AutoCompleteMode = AutoCompleteMode.SuggestAppend
If Not cbb.Items.Contains(cbb.Text) Then cbb.Text = ""
End If
End Sub
Private Sub tbb_PreviewKeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.PreviewKeyDownEventArgs)
If e.KeyCode = Keys.Up Then cbb.Focus()
If e.KeyCode = Keys.Down Then tb.Focus()
End Sub
Private Sub b2_Click()
Me.Close()
End Sub
End Class
I modified your code. And now, it's working. :)