Fully owner draw a TabControl tab title bar in WinForms c#

OwnerDrawTabControl.cs

using System.Runtime.InteropServices;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Runtime.Versioning;
using System.Windows.Forms;

namespace CustomComponents
{
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    {
        public int Left, Top, Right, Bottom;

        public RECT(int left, int top, int right, int bottom)
        {
            Left = left;
            Top = top;
            Right = right;
            Bottom = bottom;
        }

        public RECT(System.Drawing.Rectangle r) : this(r.Left, r.Top, r.Right, r.Bottom) { }

        public int X
        {
            get { return Left; }
            set { Right -= (Left - value); Left = value; }
        }

        public int Y
        {
            get { return Top; }
            set { Bottom -= (Top - value); Top = value; }
        }

        public int Height
        {
            get { return Bottom - Top; }
            set { Bottom = value + Top; }
        }

        public int Width
        {
            get { return Right - Left; }
            set { Right = value + Left; }
        }

        public System.Drawing.Point Location
        {
            get { return new System.Drawing.Point(Left, Top); }
            set { X = value.X; Y = value.Y; }
        }

        public System.Drawing.Size Size
        {
            get { return new System.Drawing.Size(Width, Height); }
            set { Width = value.Width; Height = value.Height; }
        }

        public static implicit operator System.Drawing.Rectangle(RECT r)
        {
            return new System.Drawing.Rectangle(r.Left, r.Top, r.Width, r.Height);
        }

        public static implicit operator RECT(System.Drawing.Rectangle r)
        {
            return new RECT(r);
        }

        public static bool operator ==(RECT r1, RECT r2)
        {
            return r1.Equals(r2);
        }

        public static bool operator !=(RECT r1, RECT r2)
        {
            return !r1.Equals(r2);
        }

        public bool Equals(RECT r)
        {
            return r.Left == Left && r.Top == Top && r.Right == Right && r.Bottom == Bottom;
        }

        public override bool Equals(object? obj)
        {
            if (obj is RECT rect)
                return Equals(rect);
            else if (obj is System.Drawing.Rectangle rectangle)
                return Equals(new RECT(rectangle));
            return false;
        }

        public override int GetHashCode()
        {
            return ((System.Drawing.Rectangle)this).GetHashCode();
        }

        public override string ToString()
        {
            return string.Format(System.Globalization.CultureInfo.CurrentCulture, "{{Left={0},Top={1},Right={2},Bottom={3}}}", Left, Top, Right, Bottom);
        }
    }    

    [SupportedOSPlatform("Windows")]
    public static partial class Winutils
    {
        public const int WM_LBUTTONDOWN = 0x201;
        public const int WM_LBUTTONDBLCLK = 0x203;
        public const int WM_PAINT = 0x00f;
        public const int WM_ERASEBKGND = 0x00e;
        public const int WM_MOUSEMOVE = 0x200;

        [LibraryImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static partial bool ValidateRect(IntPtr hWnd, ref RECT lpRect);
    }

    [SupportedOSPlatform("Windows")]
    public class WinTabController : TabControl
    {
        private readonly SolidBrush background = new(SystemColors.ControlDark);
        private readonly SolidBrush greyedBackground = new(SystemColors.ControlDarkDark);
        private readonly SolidBrush blackBackground = new(SystemColors.ControlText);
        private int backgroundRedrawTabCount = 0;
        private bool redrawNeeded = false;

        public WinTabController() : base()
        {
            DrawMode = TabDrawMode.OwnerDrawFixed;
            DrawItem += DrawTabTitleCards;
            Padding = Point.Empty;
            Margin = System.Windows.Forms.Padding.Empty;
            Resize += RedrawClean;
            FontChanged += RedrawClean;
            Layout += RedrawClean;
        }

        private void RedrawClean(object? sender, System.EventArgs e)
        {
            redrawNeeded = true;
            Invalidate();
        }

        private void DrawTabTitleCards(object? sender, DrawItemEventArgs e)
        {
            if (sender == null) return;
            if (e.Index < 0) return;

            Font font;
            if (TabPages[e.Index].Text.Contains('*'))
                font = new Font(Font, FontStyle.Bold);
            else
                font = new Font(Font, FontStyle.Regular);

            //backgrounds
            if (e.State == DrawItemState.Selected)
            {
                var newBounds = new Rectangle(e.Bounds.X - 2, 0, e.Bounds.Width + 4, 24);
                e.Graphics.FillRectangle(background, newBounds);
                TextRenderer.DrawText(e.Graphics, TabPages[e.Index].Text, font, newBounds, SystemColors.ControlText);
            }
            else
            {
                var newBounds = new Rectangle(e.Bounds.X, 4, e.Bounds.Width, 20);
                //remove larger selection if we are the last or first box
                if (e.Index == 0)
                    e.Graphics.FillRectangle(blackBackground, new Rectangle(e.Bounds.X - 2, 0, e.Bounds.Width, 24));
                else if (e.Index == TabCount - 1)
                    e.Graphics.FillRectangle(blackBackground, new Rectangle(e.Bounds.X, 0, e.Bounds.Width + 2, 24));
                else
                    e.Graphics.FillRectangle(blackBackground, new Rectangle(e.Bounds.X, 0, e.Bounds.Width, 24));

                e.Graphics.FillRectangle(greyedBackground, newBounds);
                TextRenderer.DrawText(e.Graphics, TabPages[e.Index].Text, font, newBounds, SystemColors.ControlText);
            }
        }

        protected override void WndProc(ref Message m)
        {
            if (m.Msg == Winutils.WM_PAINT)
            {
                var graphics = Graphics.FromHwnd(m.HWnd);
                var rect = new RECT(ClientRectangle);
                //only redraw if we add or remove pages
                if (TabCount != backgroundRedrawTabCount || redrawNeeded)
                {
                    backgroundRedrawTabCount = TabCount;
                    graphics.Clear(SystemColors.ControlText);
                    redrawNeeded = false;
                }
                for (int i = 0; i < TabCount; i++)
                {
                    DrawTabTitleCards(this, new DrawItemEventArgs(graphics, Font, GetTabRect(i), i, SelectedIndex == i ? DrawItemState.Selected : DrawItemState.Default));
                }
                m.Result = 0;
                Winutils.ValidateRect(m.HWnd, ref rect);
            }
            else
            {
                base.WndProc(ref m);
            }
        }
    }
}