C#

Maybe someone can help  :)  I can’t figure out how to make this code work for borderless Form

public partial class Form1 : Form
{
    clsResize _form_resize;

    public Form1()
    {
        InitializeComponent();

        FormBorderStyle = FormBorderStyle.None;
       _form_resize = new clsResize(this);
        this.Load += _Load;
        this.Resize += _Resize;
    }
    private void _Load(object sender, EventArgs e)
    {
        _form_resize._get_initial_size();
    }

    private void _Resize(object sender, EventArgs e)
    {
        _form_resize._resize();
    }
    //
    //This part im using for resize form
    //
    private const int cGrip = 16;

    protected override void OnPaint(PaintEventArgs e)
    {
        Rectangle rc = new Rectangle(ClientSize.Width - cGrip, ClientSize.Height - cGrip, cGrip, cGrip);
        ControlPaint.DrawSizeGrip(e.Graphics, BackColor, rc);
    }

    protected override void WndProc(ref Message m)
    {
        if (m.Msg == 0x84)
        {
            Point pos = new Point(m.LParam.ToInt32());
            pos = PointToClient(pos);
            if (pos.X >= ClientSize.Width - cGrip && pos.Y >= ClientSize.Height - cGrip)
            {
                m.Result = (IntPtr)17;
                return;
            }
        }
        base.WndProc(ref m);
    }

public class clsResize
{
    List<System.Drawing.Rectangle> _arr_control_storage = new List<System.Drawing.Rectangle>();
    private bool showRowHeader = false;
    public clsResize(Form _form_)
    {
        form = _form_;
        _formSize = _form_.ClientSize;
        _fontsize = _form_.Font.Size;
    }

    private float _fontsize  { get; set; }

    private System.Drawing.SizeF _formSize {get;set; }

    private Form form { get; set; }

    public void _get_initial_size()
    {
        var _controls = _get_all_controls(form);
        foreach (Control control in _controls)
        {
            _arr_control_storage.Add(control.Bounds);          
        }
    }

    public void _resize()
    {
        double _form_ratio_width = (double)form.ClientSize.Width /(double)_formSize.Width;
        double _form_ratio_height = (double)form.ClientSize.Height / (double)_formSize.Height;
        var _controls = _get_all_controls(form);
        int _pos = -1;
        foreach (Control control in _controls)
        {
            _pos += 1;
            System.Drawing.Size _controlSize = new System.Drawing.Size((int)(_arr_control_storage[_pos].Width * _form_ratio_width),
                (int)(_arr_control_storage[_pos].Height * _form_ratio_height));

            System.Drawing.Point _controlposition = new System.Drawing.Point((int)
            (_arr_control_storage[_pos].X * _form_ratio_width),(int) (_arr_control_storage[_pos].Y * _form_ratio_height));

            control.Bounds = new System.Drawing.Rectangle(_controlposition, _controlSize);

            control.Font = new System.Drawing.Font(form.Font.FontFamily,
             (float)(((Convert.ToDouble(_fontsize) * _form_ratio_width) / 2) +
              ((Convert.ToDouble(_fontsize) * _form_ratio_height) / 2)));

        }
    }
    private static IEnumerable<Control> _get_all_controls(Control c)
    {
        return c.Controls.Cast<Control>().SelectMany(item =>
            _get_all_controls(item)).Concat(c.Controls.Cast<Control>()).Where(control => 
            control.Name != string.Empty);
    }

It works fine when FormBorderStyle.Sizable, but if FormBorderStyle.None get "System ArgumentOutOfRangeException" in this place:

_pos += 1;
System.Drawing.Size _controlSize = new System.Drawing.Size((int)(_arr_control_storage[_pos].Width * _form_ratio_width),
    (int)(_arr_control_storage[_pos].Height * _form_ratio_height));