Option Explicit

'///API///
'Windowsに擬似メッセージを送る
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

'///定数///
Private Const WM_SYSCOMMAND = &H112 'システム制御系を示す
Private Const SC_MINIMIZE = &HF020  '最小化にする
Private Const SC_MAXIMIZE = &HF030  '最大化にする
Private Const SC_RESTORE = &HF120   '元の大きさに戻す
Private Const SC_CLOSE = &HF060     '閉じる

'///関数///

'ウィンドウを最小化にする
Sub WindowMinimze(ByVal lngHWND As Long)
    Debug.Print SendMessage(lngHWND, WM_SYSCOMMAND, SC_MINIMIZE, 0&)
End Sub

'ウィンドウを最大化にする
Sub WindowMaximize(ByVal lngHWND As Long)
    Debug.Print SendMessage(lngHWND, WM_SYSCOMMAND, SC_MAXIMIZE, 0&)
End Sub

'ウィンドウを元の大きさに戻す
Sub WindowRestore(ByVal lngHWND As Long)
    Debug.Print SendMessage(lngHWND, WM_SYSCOMMAND, SC_RESTORE, 0&)
End Sub

'ウィンドウを閉じる
Sub WindowClose(ByVal lngHWND As Long)
    Debug.Print SendMessage(lngHWND, WM_SYSCOMMAND, SC_CLOSE, 0&)
End Sub

'///イベントプロシージャ///

'ウィンドウを最小化にします
Private Sub Command1_Click()
    WindowMinimze Me.hWnd
End Sub

'ウィンドウを最大化にします
Private Sub Command2_Click()
    WindowMaximize Me.hWnd
End Sub

'ウィンドウを元の大きさに戻します
Private Sub Command3_Click()
    WindowRestore Me.hWnd
End Sub

'ウィンドウを閉じます
Private Sub Command4_Click()
    WindowClose Me.hWnd
End Sub