VB6.0,用右擊任務(wù)欄,屬性,打開的窗口進(jìn)行測試,可以按取消按鈕,成功

Option Explicit
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long
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 Declare Function SetActiveWindow Lib "user32" (ByVal hwnd As Long) As Long

Private Const BM_CLICK As Long = &HF5

Private Sub Command1_Click()
Dim hwnd As Long
hwnd = FindWindow(vbNullString, "任務(wù)欄和「開始」菜單屬性") '我找的是任務(wù)欄屬性窗口,這里換成你要找的窗口標(biāo)題
'MsgBox hwnd
Dim btnhWnd As Long
btnhWnd = FindWindowEx(hwnd, 0, "Button", "取消") '取消是按按鈕的標(biāo)題,你要換成自己的內(nèi)容
MsgBox btnhWnd
SetActiveWindow hwnd

SendMessage btnhWnd, BM_CLICK, 0, 0

End Sub