>>212
漏れの環境ではうまくいってるよん。

using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Design;
using System.Windows.Forms;
using System.Windows.Forms.Design;

class TestForm : Form
{
  PropertyGrid grid;

  public TestForm() {
    grid = new PropertyGrid();
    grid.Dock = DockStyle.Fill;
    grid.SelectedObject = new Hoge();

    this.Size = new Size(300, 400);
    this.Controls.Add(grid);
  }

  [ STAThread ]
  public static void Main() {
    Application.Run( new TestForm() );
  }
}

class Hoge
{
  private string path = "";

  [
    Category("ターゲット"),
    Description("ファイルの存在するディレクトリ"),
    Editor( typeof(FolderNameEditor), typeof(UITypeEditor) )
  ]
  public string Path {
    get { return path; }
    set { path = value; }
  }
}