hButton = FindWindowEx(hWindow,  0 , "Button", "Со&хранить")

Option Explicit
'
' Win32 API Declarations
'
Private Declare Function SetCapture Lib "user32" (ByVal hWnd As Long) As Long
Private Declare Function ReleaseCapture Lib "user32" () As Long
Private Declare Function GetCursorPos Lib "user32" (lpPoint As POINTAPI) As Long
Private Declare Function WindowFromPointXY Lib "user32" Alias "WindowFromPoint" (ByVal xPoint As Long, ByVal yPoint As Long) As Long
Private Declare Function SetForegroundWindow Lib "user32" (ByVal hWnd As Long) As Long
'
Private Declare Function GetDlgCtrlID Lib "user32" (ByVal hWnd As Long) As Long
' Win32 API Structures
'
Private Type POINTAPI
   x As Long
   y As Long
End Type
'
' Form-level member variables
'
Private m_hWnd As Long
Private m_Picking As Boolean

Private Sub Command1_Click()
   '
   ' Attempt to paste something into
   ' selected window.
   '
   If m_hWnd Then
      Clipboard.Clear
      Clipboard.SetText "Hello from VB5!", vbCFText
      Call SetForegroundWindow(m_hWnd)
      SendKeys "^v", True
   End If
End Sub

Private Sub Form_Load()
   '
   ' Assign dragging pointer
   '
   Picture1.Picture = Picture1.DragIcon
   Me.MouseIcon = Picture1.DragIcon
End Sub

Private Sub Picture1_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)
   '
   ' Clear picture and turn on dragging mousepointer.
   '
   Me.MousePointer = vbCustom
   Set Picture1.Picture = Nothing
   '
   ' Remember that we're currently picking a window.
   '
   m_Picking = True
   '
   ' Capture all mousemovements from this point until
   ' the user releases the mouse button.
   '
   Call SetCapture(Picture1.hWnd)
End Sub

Private Sub Picture1_MouseMove(Button As Integer, Shift As Integer, x As Single, y As Single)
   Static pt As POINTAPI
   Static hWnd As Long
   '
   ' If user is picking a window, check window is
   ' under the cursor whenever it moves.  If it's
   ' a different window than previously, update the
   ' display to that effect.
   '
   If m_Picking Then
      Call GetCursorPos(pt)
      hWnd = WindowFromPointXY(pt.x, pt.y)
      If hWnd <> m_hWnd Then
         m_hWnd = hWnd
         Me.Caption = Hex(m_hWnd) & " - " & GetDlgCtrlID(m_hWnd)
      End If
   End If
End Sub

Private Sub Picture1_MouseUp(Button As Integer, Shift As Integer, x As Single, y As Single)
   '
   ' We're done picking now
   '
   m_Picking = False
   '
   ' Restore dragging icon to picture box,
   ' and return mousepointer to normal.
   '
   Picture1.Picture = Picture1.DragIcon
   Me.MousePointer = vbDefault
   '
   ' Don't need to be notified anymore.
   '
   Call ReleaseCapture
   '
   ' The chosen window is already stored in m_hWnd!
   '
   MsgBox "You picked hWnd: " & Hex(m_hWnd) & Chr( 13 ) & "You picked ID: " & GetDlgCtrlID(m_hWnd)
End Sub

SendMessage Hwnd, WM_SETTEXT,  0 , ByVal "Text"

SendMessage Hwnd, WM_SETTEXT,  0 , ByVal "Text"

   Private Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
    
    ....
    ReDim lHandles( 0 ) As Long
    l = EnumChildWindows(HwndWin, AddressOf EnumChildWindowsProc,  0 )
    For j =  1  To UBound(lHandles)
    If GetDlgCtrlID(lHandles(j)) = ID Then SendMessage lHandles(j), WM_SETTEXT,  0 , ByVal "Text": Exit For
    Next
    ....

'Модуль
Option Explicit
Global lHandles() As Long
Function EnumChildWindowsProc(ByVal wHandle As Long, lParam As Long) As Long
    ReDim Preserve lHandles(UBound(lHandles) +  1 )
    lHandles(UBound(lHandles)) = wHandle
    EnumChildWindowsProc = True
End Function