【ソース】不規則矩形フォームの設計

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace SmsSend
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
            this.BackColor = SystemColors.ActiveCaptionText;
            this.TransparencyKey = Color.White;
            this.FormBorderStyle = FormBorderStyle.None;
            this.BackgroundImage = Properties.Resources._1;
        }
    }
}