gistfile1.cs

using System;
using System.Windows.Forms;

public class Form1 : Form
{
	public Form1()
	{
		this.AllowDrop = true;
		this.DragEnter += new System.Windows.Forms.DragEventHandler(this.button1_DragEnter);
		this.DragDrop += new System.Windows.Forms.DragEventHandler(this.button1_DragDrop);
	}

	private void button1_DragEnter(object sender, System.Windows.Forms.DragEventArgs e)
	{
		if(e.Data.GetDataPresent(DataFormats.FileDrop))
			e.Effect = DragDropEffects.All;
		else
			e.Effect = DragDropEffects.None;
	}

	private void button1_DragDrop(object sender, System.Windows.Forms.DragEventArgs e)
	{
		string[] s = (string[]) e.Data.GetData(DataFormats.FileDrop, false);
		foreach(string str in s)
			MessageBox.Show(str);
	}

	[STAThread]
	static void Main(string[] args)
	{
		Application.Run(new Form1());
	}
}