Option Explicit
 
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function BringWindowToTop Lib "user32" (ByVal hwnd As Long) As Long
 
Private Const WM_SYSKEYUP = &H105
Private Const WM_SYSKEYDOWN = &H104
 
Private Const VK_F4 As Long = &H73
 
Private Sub Command1_Click()
    Dim vHWND As Long
    vHWND = FindWindow("CalcFrame", vbNullString)
 
    Call BringWindowToTop(vHWND)
 
    Call PostMessage(vHWND, WM_SYSKEYDOWN, VK_F4, &H3E0001 Or &H20000000)
    Call PostMessage(vHWND, WM_SYSKEYUP, VK_F4, &H3E0001 Or &H20000000)
End Sub