実際には、コンボボックスの MouseUp イベントと共に PreviewKeyDown イベントを使用できます。
Dim UsePanelScroll As Boolean = False
Private Sub ComboBox_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
'some code
If UsePanelScroll = True Then
Panel1.Focus()
End If
End Sub
Private Sub ComboBox_PreviewKeyDown(sender As Object, e As System.Windows.Forms.PreviewKeyDownEventArgs)
Select Case e.KeyCode
Case Keys.Tab, Keys.Up, Keys.Down
UsePanelScroll = False
Case Else
UsePanelScroll = True
End Select
End Sub
Private Sub ComboBox_MouseUp(sender As System.Object, e As System.Windows.Forms.MouseEventArgs)
If e.Button = Windows.Forms.MouseButtons.Left Then
UsePanelScroll = True
End If
End Sub