Why doesn't BackColor work for TabControls in .NET?

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Dim r As Rectangle = tabControl1.GetTabRect(tabControl1.TabPages.Count-1)
Dim rf As RectangleF = New RectangleF(r.X + r.Width, r.Y - 5, tabControl1.Width - (r.X + r.Width), r.Height + 5)
Dim b As Brush = New SolidBrush(Color.White)
e.Graphics.FillRectangle(b, rf)

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