对combox的操作

Option Explicit

Private Sub Command1_Click()
    SendMessage Combo1.hwnd, CB_SHOWDROPDOWN, True, ByVal 0&
End Sub

Private Sub Command2_Click()
    SendMessage Combo1.hwnd, CB_SHOWDROPDOWN, False, ByVal 0&
End Sub
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Option Explicit

Public Const CB_SHOWDROPDOWN = &H14F
Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long