Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Me.FormBorderStyle = Windows.Forms.FormBorderStyle.None
Me.TransparencyKey = System.Drawing.SystemColors.Control
Me.AutoSize = True
Me.AutoSizeMode = Windows.Forms.AutoSizeMode.GrowAndShrink
PictureBox1.Image = System.Drawing.Image.FromFile(Application.StartupPath + "\picture\cs2.png")
PictureBox1.SizeMode = PictureBoxSizeMode.AutoSize
PictureBox1.ContextMenuStrip = ContextMenuStrip1
PictureBox1.Dock = DockStyle.Fill
End Sub

图片的问题

要么是图片本身有白边，要么是图片格式不适合。图片格式不适合时vs会自动转换格式，这种转换是有损的。