При запуске проекта теряется свойство user-контрола, установленное в дизайнере - Visual Basic .NET

Partial Public Class Canvas
    Inherits UserControl
#Region "Переменные"
    Private m_BitmapImage As Bitmap
    Private m_BackColor As Color
#End Region
#Region "Свойства"
    Public Property BitmapImage() As Bitmap
        Get
            Return m_BitmapImage
        End Get
        Set(ByVal value As Bitmap)
            m_BitmapImage = value
        End Set
    End Property
    Public Overrides Property BackColor() As Color
        Get
            Return m_BackColor
        End Get
        Set(ByVal value As Color)
            m_BackColor = value
            Me.Invalidate()
        End Set
    End Property
#End Region
#Region "Конструктор"
    Public Sub New()
        InitializeComponent()
        BitmapImage = New Bitmap(Me.Width, Me.Height)
    End Sub
#End Region
    Private Sub PaintCanvas_Load(ByVal sender As Object, ByVal e As EventArgs) Handles MyBase.Load
        Clear()
    End Sub
    Public Sub Clear()
        Dim br As New SolidBrush(Me.BackColor)
        Using g As Graphics = Graphics.FromImage(BitmapImage)
            g.FillRectangle(br, New Rectangle(Me.Location, Me.Size))
        End Using
        Me.Invalidate()
    End Sub
    Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
        MyBase.OnPaint(e)
        e.Graphics.DrawImage(Me.BitmapImage, 0, 0)
    End Sub
    Public Sub Line(ByVal aPen As Pen, ByVal x1 As Single, ByVal y1 As Single, ByVal x2 As Single, ByVal y2 As Single)
        Using g As Graphics = Graphics.FromImage(BitmapImage)
            g.DrawLine(aPen, x1, y1, x2, y2)
            Me.Invalidate()
        End Using
    End Sub
End Class

Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim pen As New Pen(Color.Red, 10)
        Canvas1.Line(pen, 20, 30, 250, 400)
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Canvas1.Clear()
    End Sub
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        Canvas1.BackColor = Color.Green
    End Sub
End Class