Option Explicit
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Integer, ByVal lParam As Any) As Long
Private Const WM_CLOSE = &H10
Function myHandle(Titulo) As Long
Dim winHwnd As Long
winHwnd = FindWindow(vbNullString, Titulo)
myHandle = winHwnd
End Function
Private Sub Command1_Click()
Dim lHwd As Long
lHwd = myHandle(Me.Text1)
If lHwd > 0 Then
Call SendMessage(lHwd, WM_CLOSE, 0, ByVal CStr(1))
End If
End Sub