i think you should override Paint method.
Private Sub ToolStripMenuItem1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles ToolStripMenuItem1.Paint
DirectCast(sender, ToolStripMenuItem).DisplayStyle = ToolStripItemDisplayStyle.None
e.Graphics.DrawImage(My.Resources.attach, 0, 0, e.ClipRectangle.Width, e.ClipRectangle.Height)
End Sub