让Combo自动打开或收起

Option Explicit
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Const CB_SHOWDROPDOWN = &H14F

Private Sub Combo1_Change()
    '打开
    Call SendMessage(Combo1.hWnd, CB_SHOWDROPDOWN, 1, ByVal 0&)
    '收起
    'Call SendMessage(Combo1.hWnd, CB_SHOWDROPDOWN, 0, ByVal 0&)
End Sub

Private Sub Form_Load()
Combo1.AddItem "001", 0
Combo1.AddItem "002", 1
Combo1.AddItem "003", 2
End Sub