Public Class Form1
    Declare Auto Function GetWindowRect Lib "User32" (ByVal hWnd As IntPtr, _
      ByRef lpRect As Rect) As Int32
    Declare Function IsWindowVisible Lib "user32" (ByVal hwnd As IntPtr) As _
    Boolean
    Public Structure Rect
        Public Left As Int32
        Public Top As Int32
        Public Right As Int32
        Public Bottom As Int32
    End Structure
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        ListBox1.Items.Clear()
        For Each p As Process In Process.GetProcesses
            If IsWindowVisible(p.MainWindowHandle) AndAlso p.MainWindowTitle _
              <> String.Empty Then
                Dim r As New Rect
                GetWindowRect(p.MainWindowHandle, r)
                Dim re As New Rectangle(r.Left, r.Top, r.Right - r.Left, _
                  r.Bottom - r.Top)
                ListBox1.Items.Add(p.MainWindowTitle & " : " & re.ToString)
            End If
        Next
    End Sub
End Class