Class Window1 

    Private flg As Boolean = False
    Private x As Integer
    Private y As Integer

    Private Sub Window1_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseEventArgs) Handles MyBase.MouseMove
        If flg Then
            Dim xx As Integer = Me.PointToScreen(e.GetPosition(Me)).X
            Dim yy As Integer = Me.PointToScreen(e.GetPosition(Me)).Y
            Me.Left += xx - x
            Me.Top += yy - y
            x = xx
            y = yy
        End If
    End Sub

    Private Sub Window1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseButtonEventArgs) Handles MyBase.MouseDown
        If e.LeftButton Then
            Me.CaptureMouse()
            flg = True
            x = Me.PointToScreen(e.GetPosition(Me)).X
            y = Me.PointToScreen(e.GetPosition(Me)).Y
        End If
    End Sub

    Private Sub Window1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Input.MouseButtonEventArgs) Handles Me.MouseUp
        flg = False
        Me.ReleaseMouseCapture()
    End Sub

End Class