Dim r As New Region(New Rectangle(Me.ClientRectangle.Left, _
  Me.ClientRectangle.Top + ToolStrip1.Height, _
Me.ClientSize.Width, Me.ClientSize.Height - ToolStrip1.Height - _
StatusStrip1.Height))
Dim ShadowBrush As SolidBrush = New SolidBrush(Color.FromArgb(128, 0, 0, 0))
Dim g As Graphics = e.Graphics
For i As Integer = 0 To Me.Width - 8 Step 8
	For j As Integer = 0 To Me.Height - 8 Step 8
		r.Exclude(New RectangleF(i, j, 4, 4))
	Next
Next
Me.Region = r
g.FillRegion(ShadowBrush, Me.Region)

Salzburger