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
'拉下combox
SendMessage Combo1.hwnd, CB_SHOWDROPDOWN, True, ByVal 0&
'收起combox
SendMessage Combo1.hwnd, CB_SHOWDROPDOWN, False, ByVal 0&