Runtime add item to PropertyGrid Drop-down List

This sample demonstrates the technique for setting two items of a property grid from the drop-down list. These items have the type of string, but it must be simple to remake them for any other type.
Firstly, inherit the class from UITypeEditor:

public class SelEditor : System.Drawing.Design.UITypeEditor
 {       
//this is a container for strings, which can be picked-out
  ListBox Box1 = new ListBox();
  IWindowsFormsEditorService edSvc;
//this is a string array for drop-down list
  public static string[] strList;
  public SelEditor()
  {
   Box1.BorderStyle=BorderStyle.None;
//add event handler for drop-down box when item will be selected
   Box1.Click+=new EventHandler(Box1_Click);
  }
  public override System.Drawing.Design.UITypeEditorEditStyle GetEditStyle
(System.ComponentModel.ITypeDescriptorContext context)
  {
   return UITypeEditorEditStyle.DropDown;
  }
  // Displays the UI for value selection.
  public override object EditValue
(System.ComponentModel.ITypeDescriptorContext context, System.IServiceProvider provider, object
value)
  {
   Box1.Items.Clear();
   Box1.Items.AddRange(strList);
   Box1.Height=Box1.PreferredHeight;
   // Uses the IWindowsFormsEditorService to display a
   // drop-down UI in the Properties window.
   edSvc = (IWindowsFormsEditorService)provider.GetService(typeof
(IWindowsFormsEditorService));
   if( edSvc != null )
   {
    edSvc.DropDownControl( Box1 );
    return Box1.SelectedItem;
   }
   return value;
  }
  private void Box1_Click(object sender, EventArgs e)
  {
   edSvc.CloseDropDown();
  }
 }

Secondly, describe a property in the class, displayed in the property grid:

 public class Class1
 {
//These are string arrays for different drop-down list.
  string[] Str1= {"AAA","BBB","CCC","DDDD"};
  string[] Str2= {"WW","EEE"};
  string s1,s2;
  public Class1()
  {
   //
   // TODO: Add constructor logic here
   //
  }

  [EditorAttribute(typeof(SelEditor), typeof(System.Drawing.Design.UITypeEditor))]
  public string STR_1
  {
   get{SelEditor.strList=Str1; return s1;}
   set{s1=value;}
  }
 
  [EditorAttribute(typeof(SelEditor), typeof(System.Drawing.Design.UITypeEditor))]
  public string STR_2
  {
   get{SelEditor.strList=Str2; return s2;}
   set{s2=value;}
  }
 }

Dynamic Properties for PropertyGrid

http://www.codeproject.com/Articles/189521/Dynamic-Properties-for-PropertyGrid
http://www.codeproject.com/Articles/11383/Hiding-Inherited-Properties-from-the-PropertyGrid
http://www.codeproject.com/Articles/48015/Exploring-the-Behaviour-of-Property-Grid

Add Custom Event to PropertyGrid CollectionEditor

http://www.codeproject.com/Articles/58286/PropertyGrid-Collection-Events

Sample code to customize the .Net PropertyGrid

Sample code to customize  the .Net PropertyGrid:

Add Custom Properties to a PropertyGrid:
http://www.codeproject.com/KB/vb/PropertyGridEx.aspx

Filtering properties in a PropertyGrid:
http://www.codeproject.com/KB/cs/FilteredPropertyGrid.aspx

PropertyGrid Utilities
http://www.codeproject.com/Articles/7852/PropertyGrid-utilities

Validating Properties In A .Net Propertygrid Control

The easiest way to validate a certain property in a .Net propertygrid control is using the PropertyValueChanged event.The code bellow shows how to limit the valid range of Age property to be 1-150

using System.Windows.Forms;
namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            //init person object
            Person person = new Person();
            person.FirstName = "George";
            person.Age = 33;
            propertyGrid.SelectedObject = person;
            propertyGrid.PropertyValueChanged+=  new PropertyValueChangedEventHandler( propertyGrid_PropertyValueChanged );
        }

        private void propertyGrid_PropertyValueChanged(object s, PropertyValueChangedEventArgs e)
        {
            if (e.ChangedItem.Label == "Age" && !IsAgeValid((int)e.ChangedItem.Value) )
            {
                // the entered age value is wrong - show error message
                e.ChangedItem.PropertyDescriptor.SetValue( propertyGrid.SelectedObject, e.OldValue);
                MessageBox.Show("Wrong age", "Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
            }
        }

        ///<summary>
        /// Determines whether age is valid
        /// </summary>
        /// <param name="age">The age.</param>
        /// <returns>
        /// <c>true</c> if is age valid ; otherwise, <c>false</c>.
        /// </returns>
        private static bool IsAgeValid( int age )
        {
            return ((age > 0) && (age < 150));
        }
    }
}

Getting Started on the .NET Framework PropertyGrid Control

Steps on creating a .Net property grid control

http://msdn.microsoft.com/en-us/library/aa302326.aspx