using System;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        private UC1 uc1 = new UC1();
        private UC2 uc2 = new UC2();

        public Form1()
        {
            InitializeComponent();
        }

        private void buttonUC1_Click(Object sender, EventArgs e)
        {
            displayPanel.Controls.Clear();
            displayPanel.Controls.Add(uc1);
        }

        private void buttonUC2_Click(Object sender, EventArgs e)
        {
            displayPanel.Controls.Clear();
            displayPanel.Controls.Add(uc2);
        }

        /// <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();
                uc1.Dispose();
                uc2.Dispose();
            }
            base.Dispose(disposing);
        }
    }
}

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class UC1 : UserControl
    {
        private Int32 count;

        public UC1()
        {
            InitializeComponent();
        }

        private void button_Click(Object sender, EventArgs e)
        {
            count++;
            textBoxCount.Text = count.ToString();
        }
    }
}

using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class UC2 : UserControl
    {
        public UC2()
        {
            InitializeComponent();
        }

        private async void button1_Click(Object sender, EventArgs e)
        {
            Application.UseWaitCursor = true;
            await Task.Run(() => Thread.Sleep(5000));
            Application.UseWaitCursor = false;
        }
    }
}