Получить hwnd окна экземпляра

Private Sub Form_Load()
  If App.PrevInstance Then Вернуть_ее_hwnd
End Sub

Option Explicit
 
Private Declare Function CreateFileMapping Lib "kernel32" Alias "CreateFileMappingA" (ByVal hFile As Long, lpFileMappingAttributes As Any, ByVal flProtect As Long, ByVal dwMaximumSizeHigh As Long, ByVal dwMaximumSizeLow As Long, ByVal lpName As String) As Long
Private Declare Function MapViewOfFile Lib "kernel32" (ByVal hFileMappingObject As Long, ByVal dwDesiredAccess As Long, ByVal dwFileOffsetHigh As Long, ByVal dwFileOffsetLow As Long, ByVal dwNumberOfBytesToMap As Long) As Long
Private Declare Function UnmapViewOfFile Lib "kernel32" (ByVal lpBaseAddress As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Declare Function GetMem4 Lib "msvbvm60" (Src As Any, Dst As Any) As Long
 
Private Const ERROR_ALREADY_EXISTS = 183&
Private Const PAGE_READWRITE = 4&
Private Const FILE_MAP_WRITE = &H2
 
Dim hMap As Long
 
Private Sub Form_Load()
    Dim ptr As Long, e As Long, hPrev As Long
    hMap = CreateFileMapping(-1, ByVal 0&, PAGE_READWRITE, 0, 4, "MyPrevAppInst"): e = Err.LastDllError
    If hMap = 0 Then MsgBox "Err create file mapping": End
    ptr = MapViewOfFile(hMap, FILE_MAP_WRITE, 0, 0, 0)
    If ptr = 0 Then
        MsgBox "Projection error"
        CloseHandle hMap
        End
    End If
    If e = ERROR_ALREADY_EXISTS Then
        ' Ýêçåìïëÿð óæå çàïóùåí
        GetMem4 ByVal ptr, hPrev
        UnmapViewOfFile ptr
        CloseHandle hMap
        MsgBox "Ýêçåìïëÿð çàïóùåí hwnd: " & hPrev
        End
    End If
    GetMem4 CLng(Me.hWnd), ByVal ptr
    UnmapViewOfFile ptr
End Sub
 
Private Sub Form_Unload(Cancel As Integer)
    CloseHandle hMap
End Sub