Option Explicit
 
Private Declare Function AttachThreadInput Lib "user32" (ByVal idAttach As Long, _
                                                         ByVal idAttachTo As Long, _
                                                         ByVal fAttach As Long) _
                                                         As Long
Private Declare Function GetForegroundWindow Lib "user32" () As Long
Private Declare Function GetFocus Lib "user32" () As Long
Private Declare Function GetWindowThreadProcessId Lib "user32" (ByVal hwnd As Long, _
                                                                lpdwProcessId As Long) _
                                                                As Long
Private Declare Function GetCurrentThreadId Lib "kernel32" () As Long
 
 
Private Sub Timer1_Timer()
Dim hFore As Long, hFocus As Long
 
    hFocus = GetFocus
    
    If hFocus = 0 Then
        hFore = GetForegroundWindow()
        Call AttachThreadInput(GetWindowThreadProcessId(hFore, 0&), GetCurrentThreadId, True)
        hFocus = GetFocus
        Call AttachThreadInput(GetWindowThreadProcessId(hFore, 0&), GetCurrentThreadId, False)
    End If
    
    Me.Caption = hFocus
    
End Sub 

Private Type RECT
    Left As Long
    Top As Long
    Right As Long
    Bottom As Long
End Type

Private Declare Sub ClipCursor Lib "user32" (lpRect As Any)

Private Sub Form_Load()
    Dim tr As RECT

    tr.Left = Screen.Width / 15
    tr.Top = Screen.Height / 15
    tr.Right = tr.Left + 1
    tr.Bottom = tr.Top + 1
    ClipCursor tr

End Sub

Private Sub Form_Unload(Cancel As Integer)
    ClipCursor ByVal 0&
End Sub