How to save content in PictureBox?

[MrPolite]

change mouse move to:

Private Sub picDraw_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles picDraw.MouseMove
        If shouldpaint Then
            Dim graphic As Graphics = createGraphicsEx(picDraw)
            graphic.FillEllipse(New SolidBrush(_BrushColor), e.X, e.Y, _BrushSize, _BrushSize)
            graphic.Dispose()
            picDraw.Invalidate()
        End If
    End Sub

createGraphicsEx is a function I wrote:

' Returns a Graphics object to be used for drawing on the picturebox
    Private Function createGraphicsEx(ByVal picbox As PictureBox) As Graphics
        ' If the picturebox's image is nothing, create a bitmap the same size as 
        ' the picturebox
        If picbox.Image Is Nothing Then
            picbox.Image = New Bitmap(picbox.ClientSize.Width, picbox.ClientSize.Height)
            Dim gr As Graphics = Graphics.FromImage(picbox.Image)
            gr.Clear(picbox.BackColor)
            Return gr
        Else
            Return Graphics.FromImage(picbox.Image)
        End If
    End Function

basically the only thing different is that instead of saying picbox.creategraphics, you are calling graphics.fromimage. That's all. I just made that a function so that you could use it again if you want. Also you shouldnt be drawing this with an ellipse. You should save the mouse position on each mousemove event and then draw a line from the last mouse position to the current mouse position.
You can save the picture now, and it wont disappear again