Visual Basic

<pre lang = "vb">
<pre>VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "Form1"
   ClientHeight    =   1995
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   4185
   LinkTopic       =   "Form1"
   ScaleHeight     =   1995
   ScaleWidth      =   4185
   StartUpPosition =   3  'Windows Default
   Begin VB.Timer Timer1 
      Left            =   540
      Top             =   930
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
 

Private Declare Function GetForegroundWindow Lib "user32" () 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 Sub Form_Load()
    Timer1.Interval = 100
End Sub
    
Private Sub Timer1_Timer()
    Static lHwnd As Long
    Dim lCurHwnd As Long
    Dim sText As String * 255
    
    lCurHwnd = GetForegroundWindow
    If lCurHwnd = lHwnd Then Exit Sub
    lHwnd = lCurHwnd
    If lHwnd <> hwnd Then
        Caption = "ActiveWidow: " & Left$(sText, GetWindowText(lHwnd, ByVal sText, 255))
        Debug.Print Caption
    Else
        Caption = "ActiveWindow: Form1"
    End If
End Sub