主题：关于picturebox的属性

Private pictureBox1 As New PictureBox()
Public Sub CreateBitmapAtRuntime() 
    pictureBox1.Size = New Size(210, 110)
    Me.Controls.Add(pictureBox1)
    Dim flag As New Bitmap(200, 100)
    Dim flagGraphics As Graphics = Graphics.FromImage(flag)
    Dim red As Integer = 0
    Dim white As Integer = 11
    While white <= 100
        flagGraphics.FillRectangle(Brushes.Red, 0, red, 200, 10)
        flagGraphics.FillRectangle(Brushes.White, 0, white, 200, 10)
        red += 20
        white += 20
    End While
    pictureBox1.Image = flag
End Sub 

以上是msdn的一个例子，为什么ft就没有Graphics和size属性呢？