Обмен данными между своими прогами через WM_COPYDATA

Option Explicit
Private Type COPYDATASTRUCT
    dwData As Long
    cbData As Long
    lpData As Long
End Type
Private Const WM_COPYDATA = &H4A
Private Const GWL_WNDPROC& = (-4&)
 
Private Const SET_RADIUS = 1
 
Private Declare Function CallWindowProcA Lib "user32" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal MSG As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function SendMessageA Lib "user32" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
Private Declare Function GetMem4 Lib "msvbvm60" (ByVal pSrc As Long, ByVal pDst As Long) As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
Private Declare Function GetWindowTextLength Lib "user32" Alias "GetWindowTextLengthA" (ByVal hwnd As Long) As Long
Private Declare Function EnumWindows Lib "user32" (ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
 
Dim pPrevWndProc As Long, fndHwnd As Long, Disable As Boolean
 
Public Sub Hook(hwnd As Long)
    pPrevWndProc = SetWindowLong(hwnd, GWL_WNDPROC, AddressOf WindowProc)
End Sub
Public Sub UnHook(hwnd As Long)
    Call SetWindowLong(hwnd, GWL_WNDPROC, pPrevWndProc)
End Sub
Public Function SendRadius() As Boolean
    Dim CDRec As COPYDATASTRUCT, Value As Long
    If fndHwnd = 0 Then EnumWindows AddressOf EnumWnd, 0
    If fndHwnd Then
        Value = frmMain.Radius
        CDRec.dwData = SET_RADIUS
        CDRec.cbData = 4
        CDRec.lpData = VarPtr(Value)
        Disable = True
        SendMessageA fndHwnd, WM_COPYDATA, frmMain.hwnd, CDRec
        Disable = False
    End If
End Function
Private Function EnumWnd(ByVal hwnd As Long, ByVal lParam As Long) As Boolean
    Dim Cap As String, L As Long
    L = GetWindowTextLength(hwnd)
    Cap = Space$(L)
    GetWindowText hwnd, Cap, L + 1
    If Cap = "Circle" And hwnd <> frmMain.hwnd Then fndHwnd = hwnd: Exit Function
    If hwnd = 0 Then Stop
    EnumWnd = True
End Function
Private Function WindowProc(ByVal hwnd As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
    Select Case uMsg
    Case WM_COPYDATA
        Dim CDRec As COPYDATASTRUCT, Value As Long
        CopyMemory CDRec, ByVal lParam, LenB(CDRec)
        Select Case CDRec.dwData
        Case SET_RADIUS
            If CDRec.cbData <> 4 Or Disable Then Exit Function
            GetMem4 CDRec.lpData, VarPtr(Value)
            frmMain.Radius = Value
            frmMain.hsbRadius.Value = frmMain.Radius
            WindowProc = True
        End Select
    Case Else
        WindowProc = CallWindowProcA(pPrevWndProc, hwnd, uMsg, wParam, lParam)
    End Select
End Function

Option Explicit
Dim mRadius As Long, fndHwnd As Long, Tmp As Boolean
 
Public Property Get Radius() As Long
    Radius = mRadius
End Property
Public Property Let Radius(ByVal Value As Long)
    If Value > 100 Then Value = 100
    If Value < 1 Then Value = 1
    Tmp = True
    mRadius = Value
    hsbRadius.Value = mRadius
    Me.Cls
    Me.Circle (Me.ScaleWidth / 2, Me.ScaleHeight / 2), mRadius
    Me.Refresh
    SendRadius
End Property
 
Private Sub Form_Load()
    Hook Me.hwnd
End Sub
 
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
    UnHook Me.hwnd
End Sub
 
Private Sub hsbRadius_Change()
    If Not Tmp Then Me.Radius = hsbRadius.Value Else Tmp = False
End Sub
Private Sub hsbRadius_Scroll()
    Call hsbRadius_Change
End Sub