Border Around Tab

public override void DrawTabStripBackground(PaintEventArgs e, Rectangle bounds, TabStrip tabStrip) {
    // Fill the background
    tabStripBackgroundFill.Draw(e.Graphics, bounds, TabStrip.GetSidesFromTabStripTabAlignment(tabStrip.TabAlignment));

    // Fill in the tab container
    Rectangle tabContainerBounds;
    switch (tabStrip.TabAlignment) {
        case TabStripTabAlignment.Left:
            tabContainerBounds = new Rectangle(bounds.Left, bounds.Top, 
                this.TabStripTabOuterMargin + tabStrip.TabAscent, bounds.Height);
            break;
        case TabStripTabAlignment.Right:
            tabContainerBounds = new Rectangle(
                bounds.Right - (this.TabStripTabOuterMargin + tabStrip.TabAscent), 
                bounds.Top, this.TabStripTabOuterMargin + tabStrip.TabAscent, bounds.Height);
            break;
        case TabStripTabAlignment.Bottom:
            tabContainerBounds = new Rectangle(bounds.Left, 
                bounds.Bottom - (this.TabStripTabOuterMargin + tabStrip.TabAscent), bounds.Width, 
                this.TabStripTabOuterMargin + tabStrip.TabAscent);
            break;
        default: // Top
            tabContainerBounds = new Rectangle(bounds.Left, bounds.Top, bounds.Width, 
                this.TabStripTabOuterMargin + tabStrip.TabAscent);
            break;
    }
    tabStripTabContainerBackgroundFill.Draw(e.Graphics, tabContainerBounds, TabStrip.GetSidesFromTabStripTabAlignment(tabStrip.TabAlignment));

    // Draw a border
    Pen borderPen = new Pen(this.TabStripTabSelectedBorderColor);
    switch (tabStrip.TabAlignment) {
        case TabStripTabAlignment.Left:
            e.Graphics.DrawLine(borderPen, bounds.Left + (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1), bounds.Top, 
                bounds.Left + (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1), bounds.Bottom - 1);
            break;
        case TabStripTabAlignment.Right:
            e.Graphics.DrawLine(borderPen, bounds.Right - (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1) - 1, bounds.Top, 
                bounds.Right - (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1) - 1, bounds.Bottom - 1);
            break;
        case TabStripTabAlignment.Bottom:
            e.Graphics.DrawLine(borderPen, bounds.Left, bounds.Bottom - (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1) - 1, 
                bounds.Right - 1, bounds.Bottom - (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1) - 1);
            break;
        default: // Top
            e.Graphics.DrawLine(borderPen, bounds.Left, bounds.Top + (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1), 
                bounds.Right - 1, bounds.Top + (this.TabStripTabOuterMargin + tabStrip.TabAscent - 1));
            break;
    }
    borderPen.Dispose();
}