C#

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 TestCopyFolder
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
    }
}

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

namespace TestCopyFolder
{
    public partial class ucCopyDir : UserControl
    {
        public ucCopyDir()
        {
            InitializeComponent();
        }

        private void txtBoxCpSrc_DragEnter(object sender, DragEventArgs e)
        {
            // Drag and drop effect in windows
            if (e.Data.GetDataPresent(DataFormats.FileDrop, false) == true)
            {
                e.Effect = DragDropEffects.All;
            }
        }

        // Source Drag and Drop section
        private void txtBoxCpSrc_DragDrop(object sender, DragEventArgs e)
        {
            // This just allows you to drop a file into the source textbox and display it's path.
            string[] files1 = (string[])e.Data.GetData(DataFormats.FileDrop,false);
            foreach (string file1 in files1)
                txtBoxCpSrc.Text = file1;
        }

        private void btnCpSrcBrowse_Click(object sender, EventArgs e)
        {
            FolderBrowserDialog fbd = new FolderBrowserDialog();
            if (fbd.ShowDialog() == DialogResult.OK)
            {
                txtBoxCpSrc.Text = (fbd.SelectedPath);
            }
        }
    }
}