''' <summary>
''' Prüft, ob eine bestimmte Form bereits geladen ist
''' und gibt im Erfolgsfall True zurück
''' </summary>
''' <param name="sName">Name des Form-Objekts</param>
Public Function FormIsLoaded(ByVal sName As String) As Form
  Dim bResult As Boolean = False
 
  ' alle geöffneten Forms durchlauden
  For Each oForm As Form In Application.OpenForms
    If oForm.Name.ToLower = sName.ToLower Then
      Return (oForm)
    End If
  Next
 
  Return (Nothing)
End Function

Private Sub M_BuchungEinlagerung_Click(ByVal sender As System.Object, _
  ByVal e As System.EventArgs) Handles M_BuchungEinlagerung.Click
 
  Try
    Dim oForm As Form = FormIsLoaded("frmEinlagerung")
    If oForm Is Nothing Then
      Dim oForm As New frmEinlagerung
      With oForm
        .MdiParent = Me
        .Show()
      End With
    Else
      oForm.BringToFront()
    End If
  Catch ex As Exception
    MessageBox.Show(ex.Message, "Fehler", MessageBoxButtons.OK, _
      MessageBoxIcon.Stop)
  End Try
End Sub

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