Thread: Borderless + Sizeable form

Hi, this is pretty simple, you need to use the form's MouseMove, MouseUp, and MouseDown events to create your own resize logic.

Example:

Code:

using System.Drawing;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private bool resizing = false;
        private Point last = new Point(0, 0);

        public Form1()
        {
            InitializeComponent();
            this.FormBorderStyle = FormBorderStyle.None;
        }

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {
            if (!resizing) // handle cursor type
            {
                bool resize_x = e.X > (this.Width - 8);
                bool resize_y = e.Y > (this.Height - 8);

                if (resize_x && resize_y)
                    this.Cursor = Cursors.SizeNWSE;
                else if (resize_x)
                    this.Cursor = Cursors.SizeWE;
                else if (resize_y)
                    this.Cursor = Cursors.SizeNS;
                else this.Cursor = Cursors.Default;
            }
            else // handle resize
            {
                int w = this.Size.Width;
                int h = this.Size.Height;

                if (this.Cursor.Equals(Cursors.SizeNWSE))
                    this.Size = new Size(w + (e.Location.X - this.last.X), h + (e.Location.Y - this.last.Y));
                else if (this.Cursor.Equals(Cursors.SizeWE))
                    this.Size = new Size(w + (e.Location.X - this.last.X), h);
                else if (this.Cursor.Equals(Cursors.SizeNS))
                    this.Size = new Size(w, h + (e.Location.Y - this.last.Y));

                this.last = e.Location;
            }
        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {
            this.resizing = true;
            this.last = e.Location;
        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            this.resizing = false;
        }
    }
}

This principle could also be used to make your form movable.