Private Sub Form_Load()
  ' WaitBar initialisieren
  InitWaitBar Me, picwaitbar
End Sub
Private Sub cmdStart_Click()
  ' WaitBar starten
  ShowWaitBar Me.hWnd, 25
End Sub
Private Sub cmdStop_Click()
  ' WaitBar ausblenden
  StopWaitBar Me.hWnd
End Sub

Option Explicit
' Benötigte API's für die Timer-Steuerung
Private Declare Function SetTimer Lib "user32" ( _
  ByVal hWnd As Long, _
  ByVal nIDEvent As Long, _
  ByVal uElapse As Long, _
  ByVal lpTimer As Long) As Long
Private Declare Function KillTimer Lib "user32" ( _
  ByVal hWnd As Long, _
  ByVal nIDEvent As Long) As Long
 
Private Const MY_NID = 88
 
' Legt fest, in welchen Schritten der
' Balken bewegt werden soll
Private Const nStep = 1
Private m_lblControl As Control
' WaitBar erstellen
Public Sub InitWaitBar(oForm As Form, _
  picContainer As Control, _
  Optional ByVal nBackColor As OLE_COLOR = &HFFC0C0)
 
  ' Label-Control nur erstellen, falls
  ' nicht schon erstellt.
  Dim bExists As Boolean
  Dim oControl As Control
 
  For Each oControl In oForm.Controls
    If oControl.Name = "lblWaitBar" Then
      Set m_lblControl = oControl
      bExists = True: Exit For
    End If
  Next
  ' ScaleMode auf Pixel setzen
  picContainer.ScaleMode = vbPixels
  If Not bExists Then
    ' Label erstellen
    Set m_lblControl = oForm.Controls.Add("VB.Label", _
      "lblWaitBar", picContainer)
  End If
  m_lblControl.Caption = ""
  m_lblControl.BackColor = nBackColor
End Sub
' WaitBar starten
Public Sub ShowWaitBar(ByVal hWnd As Long, _
  Optional ByVal nInterval = 15)
  Dim nResult As Long
 
  If Not m_lblControl Is Nothing Then
    With m_lblControl
      ' Label zunächst ganz nach links setzen
      .Move -.Width, 0, .Width, .Container.ScaleHeight
      .Visible = True
 
      ' Timer starten
      nResult = SetTimer(hWnd, MY_NID, nInterval, AddressOf WaitBar_TimerEvent)
    End With
  End If
End Sub
' Timer-Event!
Private Sub WaitBar_TimerEvent( _
  ByVal hWnd As Long, _
  ByVal uMsg As Long, _
  ByVal idEvent As Long, _
  ByVal dwTime As Long)
 
  Dim nLeft As Single
 
  With m_lblControl
    ' aktuelle Position
    nLeft = .Left
 
    If .Tag <> "back" Then
      ' Vorwärts! (nach rechts bewegen)
      nLeft = .Left + nStep
      If nLeft + .Width > .Container.ScaleWidth Then
        .Tag = "back"
        nLeft = .Container.ScaleWidth - .Width
      End If
    Else
      ' Rückwärts! (nach links bewegen)
      nLeft = .Left - nStep
      If nLeft < 0 Then .Tag = "": nLeft = 0
    End If
 
    ' Label positionieren
    .Left = nLeft
  End With
End Sub
' WaitBar stoppen
Public Sub StopWaitBar(ByVal hWnd As Long)
  ' Timer stoppen
  KillTimer hWnd, MY_NID
 
  ' Label wieder unsichtbar machen
  If Not m_lblControl Is Nothing Then
    m_lblControl.Visible = False
  End If
End Sub