A THINKING FRUIT ＞ C#
　SimpleTimer（シンプルなスレッドの使用方法）
※　記事としては未定完成です。
Alertform.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SingleTimer
{
    public partial class Alertform : Form
    {
        public Alertform( string strMessage, string strTitle )
        {
            InitializeComponent();

            buttonClose.Click += ButtonClose_Click;

            textMessage.Text = strMessage;
            textMessage.SelectionLength = 0;
            textMessage.SelectionStart = 0;

            this.Text = strTitle;
        }

        private void ButtonClose_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}
Alertform.Designer.cs
namespace SingleTimer
{
    partial class Alertform
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.textMessage = new System.Windows.Forms.TextBox();
            this.label1 = new System.Windows.Forms.Label();
            this.buttonClose = new System.Windows.Forms.Button();
            this.SuspendLayout();
            //
            // textMessage
            //
            this.textMessage.Font = new System.Drawing.Font("ＭＳ ゴシック", 14.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(128)));
            this.textMessage.Location = new System.Drawing.Point(11, 26);
            this.textMessage.Margin = new System.Windows.Forms.Padding(4);
            this.textMessage.Multiline = true;
            this.textMessage.Name = "textMessage";
            this.textMessage.ReadOnly = true;
            this.textMessage.ScrollBars = System.Windows.Forms.ScrollBars.Both;
            this.textMessage.Size = new System.Drawing.Size(359, 118);
            this.textMessage.TabIndex = 0;
            //
            // label1
            //
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(13, 7);
            this.label1.Margin = new System.Windows.Forms.Padding(4, 0, 4, 0);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(62, 15);
            this.label1.TabIndex = 1;
            this.label1.Text = "メッセージ";
            //
            // buttonClose
            //
            this.buttonClose.Location = new System.Drawing.Point(139, 149);
            this.buttonClose.Margin = new System.Windows.Forms.Padding(2);
            this.buttonClose.Name = "buttonClose";
            this.buttonClose.Size = new System.Drawing.Size(95, 33);
            this.buttonClose.TabIndex = 2;
            this.buttonClose.Text = "閉じる";
            this.buttonClose.UseVisualStyleBackColor = true;
            //
            // Alertform
            //
            this.AcceptButton = this.buttonClose;
            this.AutoScaleDimensions = new System.Drawing.SizeF(8F, 15F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(381, 192);
            this.Controls.Add(this.buttonClose);
            this.Controls.Add(this.label1);
            this.Controls.Add(this.textMessage);
            this.Font = new System.Drawing.Font("MS UI Gothic", 11.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(128)));
            this.Margin = new System.Windows.Forms.Padding(4);
            this.MaximizeBox = false;
            this.MinimizeBox = false;
            this.Name = "Alertform";
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterParent;
            this.Text = "Alertform";
            this.TopMost = true;
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.TextBox textMessage;
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.Button buttonClose;
    }
}
Mainform.cs
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SingleTimer
{
    public partial class Mainform : Form
    {
        public readonly string NL = System.Environment.NewLine;

        public Mainform()
        {
            InitializeComponent();

            buttonAction.Click += ButtonAction_Click;

            buttonStop.Click += ButtonStop_Click;

            buttonStop.Enabled = false;
        }

        protected override void OnClosed( EventArgs e )
        {
            m_eventCancellation.Dispose();
        }

        private void ButtonStop_Click(object sender, EventArgs e)
        {
            if( !m_eventCancellation.IsSet )
            {
                m_eventCancellation.Set();
            }
        }

        System.Threading.ManualResetEventSlim m_eventCancellation = new System.Threading.ManualResetEventSlim();

        bool m_bAction = false;

        private void EnableControl( bool bAction )
        {
            buttonAction.Enabled = m_bAction;

            m_bAction = bAction;

            buttonStop.Enabled = m_bAction;

            textMemo.ReadOnly = m_bAction;
            textTimeM.ReadOnly = m_bAction;
        }

        private async void ButtonAction_Click(object sender, EventArgs e)
        {
            if( m_bAction )
            {
                return;
            }


            string strMessage = "";

            int nTimeM;

            if( !int.TryParse(textTimeM.Text, out nTimeM) || nTimeM <= 0 )
            {
                strMessage += "時間指定が不正です。（１分以上必要です）" + NL;
            }

            if( textMemo.Text.Length == 0 )
            {
                strMessage += "メモが不正です。（１文字を以上必要です）" + NL;
            }

            if( strMessage.Length > 0 )
            {
                using( var alert = new Alertform( strMessage, Text ) )
                {
                    alert.ShowDialog( this );
                }

                return;
            }


            EnableControl( true );


            this.WindowState = FormWindowState.Minimized;


            nTimeM *= 1000 * 60;

            m_eventCancellation.Reset();


            System.Action<bool> fnShowMessage = ( bool bSignal ) =>
            {
                // bSignal == true はキャンセルした時

                if( bSignal == false )
                {
                    using( var alert = new Alertform( "指定時間を経過しました。" + NL + NL + textMemo.Text, Text ) )
                    {
                        alert.ShowDialog();
                    }
                }


                EnableControl( false );

                if( this.WindowState == FormWindowState.Minimized )
                {
                    this.WindowState = FormWindowState.Normal;
                }
            };

            await Task.Run( () =>
            {
                bool bSignal = m_eventCancellation.Wait( nTimeM );

                this.Invoke( fnShowMessage, bSignal );
            } );
        }
    }
}
Mainform.Designer.cs
namespace SingleTimer
{
    partial class Mainform
    {
        /// <summary>
        /// 必要なデザイナー変数です。
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// 使用中のリソースをすべてクリーンアップします。
        /// </summary>
        /// <param name="disposing">マネージド リソースを破棄する場合は true を指定し、その他の場合は false を指定します。</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows フォーム デザイナーで生成されたコード

        /// <summary>
        /// デザイナー サポートに必要なメソッドです。このメソッドの内容を
        /// コード エディターで変更しないでください。
        /// </summary>
        private void InitializeComponent()
        {
            this.buttonAction = new System.Windows.Forms.Button();
            this.textMemo = new System.Windows.Forms.TextBox();
            this.textTimeM = new System.Windows.Forms.TextBox();
            this.labelTime = new System.Windows.Forms.Label();
            this.labelMemo = new System.Windows.Forms.Label();
            this.buttonStop = new System.Windows.Forms.Button();
            this.labelMinutes = new System.Windows.Forms.Label();
            this.SuspendLayout();
            //
            // buttonAction
            //
            this.buttonAction.Anchor = System.Windows.Forms.AnchorStyles.Bottom;
            this.buttonAction.Location = new System.Drawing.Point(188, 131);
            this.buttonAction.Name = "buttonAction";
            this.buttonAction.Size = new System.Drawing.Size(75, 23);
            this.buttonAction.TabIndex = 5;
            this.buttonAction.Text = "実行";
            this.buttonAction.UseVisualStyleBackColor = true;
            //
            // textMemo
            //
            this.textMemo.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom)
| System.Windows.Forms.AnchorStyles.Left)
| System.Windows.Forms.AnchorStyles.Right)));
            this.textMemo.Location = new System.Drawing.Point(12, 25);
            this.textMemo.Multiline = true;
            this.textMemo.Name = "textMemo";
            this.textMemo.Size = new System.Drawing.Size(419, 100);
            this.textMemo.TabIndex = 1;
            //
            // textTimeM
            //
            this.textTimeM.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)));
            this.textTimeM.Font = new System.Drawing.Font("ＭＳ ゴシック", 11.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(128)));
            this.textTimeM.Location = new System.Drawing.Point(46, 132);
            this.textTimeM.Name = "textTimeM";
            this.textTimeM.Size = new System.Drawing.Size(71, 22);
            this.textTimeM.TabIndex = 3;
            //
            // labelTime
            //
            this.labelTime.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)));
            this.labelTime.AutoSize = true;
            this.labelTime.Location = new System.Drawing.Point(13, 138);
            this.labelTime.Name = "labelTime";
            this.labelTime.Size = new System.Drawing.Size(29, 12);
            this.labelTime.TabIndex = 2;
            this.labelTime.Text = "時間";
            //
            // labelMemo
            //
            this.labelMemo.AutoSize = true;
            this.labelMemo.Location = new System.Drawing.Point(10, 10);
            this.labelMemo.Name = "labelMemo";
            this.labelMemo.Size = new System.Drawing.Size(22, 12);
            this.labelMemo.TabIndex = 0;
            this.labelMemo.Text = "メモ";
            //
            // buttonStop
            //
            this.buttonStop.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
            this.buttonStop.DialogResult = System.Windows.Forms.DialogResult.Cancel;
            this.buttonStop.Location = new System.Drawing.Point(356, 131);
            this.buttonStop.Name = "buttonStop";
            this.buttonStop.Size = new System.Drawing.Size(75, 23);
            this.buttonStop.TabIndex = 6;
            this.buttonStop.Text = "停止";
            this.buttonStop.UseVisualStyleBackColor = true;
            //
            // labelMinutes
            //
            this.labelMinutes.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left)));
            this.labelMinutes.AutoSize = true;
            this.labelMinutes.Location = new System.Drawing.Point(122, 138);
            this.labelMinutes.Name = "labelMinutes";
            this.labelMinutes.Size = new System.Drawing.Size(25, 12);
            this.labelMinutes.TabIndex = 4;
            this.labelMinutes.Text = "[分]";
            //
            // Mainform
            //
            this.AcceptButton = this.buttonAction;
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.CancelButton = this.buttonStop;
            this.ClientSize = new System.Drawing.Size(446, 161);
            this.Controls.Add(this.buttonStop);
            this.Controls.Add(this.labelMemo);
            this.Controls.Add(this.labelMinutes);
            this.Controls.Add(this.labelTime);
            this.Controls.Add(this.textTimeM);
            this.Controls.Add(this.textMemo);
            this.Controls.Add(this.buttonAction);
            this.Name = "Mainform";
            this.Text = "SingleTimer";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.Button buttonAction;
        private System.Windows.Forms.TextBox textMemo;
        private System.Windows.Forms.TextBox textTimeM;
        private System.Windows.Forms.Label labelTime;
        private System.Windows.Forms.Label labelMemo;
        private System.Windows.Forms.Button buttonStop;
        private System.Windows.Forms.Label labelMinutes;
    }
}

Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SingleTimer
{
    static class Program
    {
        /// <summary>
        /// アプリケーションのメイン エントリ ポイントです。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Mainform());
        }
    }
}