To reproduce:

PropertyStoreItem prop1 = new PropertyStoreItem(typeof(DateTime), "Date", DateTime.Now);
PropertyStoreItem prop2 = new PropertyStoreItem(typeof(Nullable<DateTime>), "NullableDate", DateTime.Now);
PropertyStoreItem prop3 = new PropertyStoreItem(typeof(DateTime?), "Date?", DateTime.Now);

RadPropertyStore store = new RadPropertyStore();
store.Add(prop1);
store.Add(prop2);
store.Add(prop3); 
this.radPropertyGrid1.SelectedObject = store;

Open the editor for one of the properties and press the Clear button in the PropertyGridDateTimeEditor's popup. The value is cleared, but the PropertyValueButtonElement is not displayed.

Workaround: specify the initial value as default value for the property:

public Form1()
{
    InitializeComponent();

    DateTime initialValue = DateTime.Now;
    PropertyStoreItem prop1 = new PropertyStoreItem(typeof(DateTime), "Date", initialValue);
    prop1.Attributes.Add(new DefaultValueAttribute(initialValue));
    PropertyStoreItem prop2 = new PropertyStoreItem(typeof(Nullable<DateTime>), "NullableDate", initialValue);
    prop2.Attributes.Add(new DefaultValueAttribute(initialValue));
    PropertyStoreItem prop3 = new PropertyStoreItem(typeof(DateTime?), "Date?", initialValue);
    prop3.Attributes.Add(new DefaultValueAttribute(initialValue));
    
    RadPropertyStore store = new RadPropertyStore();
    store.Add(prop1);
    store.Add(prop2);
    store.Add(prop3); 
    this.radPropertyGrid1.SelectedObject = store;
     
}

To reproduce: use the following code snippet and refer to the attached gif file.

public Form1()
{
    InitializeComponent();
    this.radPropertyGrid1.SelectedObject = this;
    this.radPropertyGrid1.RightToLeft = System.Windows.Forms.RightToLeft.Yes;
}

Workaround:

public Form1()
{
    InitializeComponent();
    this.radPropertyGrid1.CreateItemElement += radPropertyGrid1_CreateItemElement;
    this.radPropertyGrid1.SelectedObject = this;
    this.radPropertyGrid1.RightToLeft = System.Windows.Forms.RightToLeft.Yes;
}

private void radPropertyGrid1_CreateItemElement(object sender, CreatePropertyGridItemElementEventArgs e)
{
    if (e.ItemElementType == typeof(PropertyGridItemElement))
    {
        e.ItemElementType = typeof(CustomPropertyGridItemElement);
    }
}

public class CustomPropertyGridItemElement : PropertyGridItemElement
{
    private bool isResizing;
    private Point downLocation;
    private int downWidth;

    protected override Type ThemeEffectiveType
    {
        get
        {
            return typeof(PropertyGridItemElement);
        }
    }

    private const int resizePointerOffset = 3;

    public override bool IsInResizeLocation(Point location)
    {
        return (location.X >= this.ControlBoundingRectangle.X + this.PropertyTableElement.ValueColumnWidth - resizePointerOffset &&
                location.X <= this.ControlBoundingRectangle.X + this.PropertyTableElement.ValueColumnWidth + resizePointerOffset);
    }

    protected override void OnMouseDown(MouseEventArgs e)
    {
        if (IsInResizeLocation(e.Location))
        {
            if (this.PropertyTableElement.IsEditing)
            {
                this.PropertyTableElement.EndEdit();
            }

            this.Capture = true;
            this.isResizing = true;
            this.downLocation = e.Location;
            this.downWidth = this.PropertyTableElement.ValueColumnWidth;
        }

        base.OnMouseDown(e);
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
        if (this.isResizing)
        {
            int delta = e.Location.X - downLocation.X;

            if (this.RightToLeft)
            {
                delta *= -1;
            }

            this.PropertyTableElement.ValueColumnWidth = downWidth - delta;
            return;
        }

        if (this.IsInResizeLocation(e.Location))
        {
            this.ElementTree.Control.Cursor = Cursors.VSplit;
        }
        else
        {
            this.ElementTree.Control.Cursor = Cursors.Default;
        }

        base.OnMouseMove(e);
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        if (this.isResizing)
        {
            this.isResizing = false;
            this.Capture = false;
        }

        base.OnMouseUp(e);
    }
}

To reproduce: use the following code snippet and refer to the attached gif file:

 public Form1()
 {
     InitializeComponent(); 
     this.radPropertyGrid1.SelectedObject = this;
 }

 private void radButton1_Click(object sender, EventArgs e)
 {
     ThemeResolutionService.ApplicationThemeName = "VisualStudio2012Dark";
 }

 private void radButton2_Click(object sender, EventArgs e)
 {
     ThemeResolutionService.ApplicationThemeName = "ControlDefault";
 }


Workaround:

private void radPropertyGrid1_EditorInitialized(object sender, PropertyGridItemEditorInitializedEventArgs e)
{
    PropertyGridTextBoxEditor editor = e.Editor as PropertyGridTextBoxEditor;
    if (editor != null)
    {
        BaseTextBoxEditorElement el = editor.EditorElement as BaseTextBoxEditorElement;
        if (el != null)
        {
            el.BackColor = Color.Black;
        }
    }
}

The PropertyChanged event does not fire when the ValueColumnWidth property is changed.

Workaround: set the RadPropertyGrid.SelectedGridItem property to null before changing the SelectedObject.

To reproduce: 

1. Add a RadPropertyGrid and populate it with all of of  items by using the following code:
                      this.radPropertyGrid1.SelectedObject = this;
2. Expand two items.
3. Scroll to the bottom.
4. Scroll to the top.
5. If you scroll to the bottom again, you will see a lot of empty space. The attached gif file illustrates better the problem.

Workaround:
public Form1()
{
    InitializeComponent();

    this.radPropertyGrid1.SelectedObject = this;
    this.radPropertyGrid1.PropertyGridElement.PropertyTableElement.Scroller.Traverser =
        new CustomPropertyGridTraverser(this.radPropertyGrid1.PropertyGridElement.PropertyTableElement);
}

public class CustomPropertyGridTraverser : PropertyGridTraverser
{
    public CustomPropertyGridTraverser(PropertyGridTableElement propertyGridElement) : base(propertyGridElement)
    {
    }

    public int Index
    {
        get
        {
            FieldInfo fi = typeof(PropertyGridTraverser).GetField("index", BindingFlags.NonPublic | BindingFlags.Instance);
            return int.Parse(fi.GetValue(this).ToString());
        }
        set 
        {
            FieldInfo fi = typeof(PropertyGridTraverser).GetField("index", BindingFlags.NonPublic | BindingFlags.Instance);
            fi.SetValue(this, value);
        }
    }

    public int GroupIndex
    {
        get
        {
            FieldInfo fi = typeof(PropertyGridTraverser).GetField("groupIndex", BindingFlags.NonPublic | BindingFlags.Instance);
            return int.Parse(fi.GetValue(this).ToString());
        }
    }

    public PropertyGridTableElement Element
    {
        get
        {
            FieldInfo fi = typeof(PropertyGridTraverser).GetField("propertyGridElement", BindingFlags.NonPublic | BindingFlags.Instance);
            return fi.GetValue(this) as PropertyGridTableElement ;
        }
    }

    public PropertyGridItemBase Item
    {
        get
        {
            FieldInfo fi = typeof(PropertyGridTraverser).GetField("item", BindingFlags.NonPublic | BindingFlags.Instance);
            return fi.GetValue(this) as PropertyGridItemBase ;
        }
        set 
        {
            FieldInfo fi = typeof(PropertyGridTraverser).GetField("item", BindingFlags.NonPublic | BindingFlags.Instance);
            fi.SetValue(this, value);
        }
    }

    protected override bool MovePreviousFromDataItem(PropertyGridItemBase currentItem)
    {
        if (currentItem.Parent != null && currentItem.Parent.GridItems.Count > 0)
        {
            if (this.Index > 0)
            {
                PropertyGridItemBase prevItem = currentItem.Parent.GridItems[--this.Index];
                if (prevItem.Expandable && (prevItem.Expanded || this.TraverseHirarchy))
                {
                    prevItem = this.GetLastChild(prevItem);
                }

                this.Item = prevItem;
                return true;
            }

            this.Item = currentItem.Parent;
            this.Index = -1;
            if (currentItem.Parent.Parent != null)
            {
                this.Index = currentItem.Parent.Parent.GridItems.IndexOf(currentItem.Parent as PropertyGridItem);
            }
            else
            {
                if (this.Element.CollectionView.Groups.Count == 0)
                {
                    this.Index = this.Element.CollectionView.IndexOf(currentItem.Parent as PropertyGridItem);
                }
                else
                {
                    this.Index = this.Element.CollectionView.Groups[this.GroupIndex].IndexOf(currentItem.Parent as PropertyGridItem);
                }
            }
            return true;
        }
        return base.MovePreviousFromDataItem(currentItem);
    }
}

Currently when expanding an item in RadPropertyGrid the order of the sub items changes on every start.

To reproduce:
 radPropertyGrid1.SelectedObject = new RadDropDownList();

The Items collection does not have a setter, but one still should be able to add items via the respective editor.

To reproduce: 
private void PopulateGrid()
{
    this.radPropertyGrid1.SortOrder = System.Windows.Forms.SortOrder.Ascending;
    PropertyStoreItem myRadProp;
  
    RadPropertyStore myRadProperties = new RadPropertyStore();

    for (int i = 0; i <= 6000; i++)
    {

        myRadProp = new PropertyStoreItem(typeof(string), "PropName" + i, "Value" + i, "Help" + i, "same");

        myRadProperties.Add(myRadProp);
    }

    radPropertyGrid1.SelectedObject = myRadProperties;
}


Workaround:

public Form1()
{
    InitializeComponent();

    radPropertyGrid1.PropertyGridElement.PropertyTableElement.ListSource.CollectionView.GroupFactory =
        new MyPropertyGridGroupFactory(this.radPropertyGrid1.PropertyGridElement.PropertyTableElement);
    this.radPropertyGrid1.SortOrder = System.Windows.Forms.SortOrder.Ascending;
    PropertyStoreItem myRadProp;

    RadPropertyStore myRadProperties = new RadPropertyStore();

    for (int i = 0; i <= 6000; i++)
    {
        myRadProp = new PropertyStoreItem(typeof(string), "PropName" + i, "Value" + i, "Help" + i, "same");

        myRadProperties.Add(myRadProp);
    }
           
    this.radPropertyGrid1.PropertyGridElement.PropertyTableElement.ListSource.BeginUpdate();
    radPropertyGrid1.SelectedObject = myRadProperties;
    this.radPropertyGrid1.PropertyGridElement.PropertyTableElement.ListSource.EndUpdate();
}

public class MyPropertyGridGroupFactory : IGroupFactory<PropertyGridItem>
{
    private PropertyGridTableElement propertyGridElement;

    public MyPropertyGridGroupFactory(PropertyGridTableElement propertyGridElement)
    {
        this.propertyGridElement = propertyGridElement;
    }

    public GroupCollection<PropertyGridItem> CreateCollection(IList<Group<PropertyGridItem>> list)
    {
        return new PropertyGridGroupCollection(list);
    }

    public Group<PropertyGridItem> CreateGroup(object key, Group<PropertyGridItem> parent, params object[] metaData)
    {
        return new MyPropertyGridGroup(key, parent, this.propertyGridElement);
    }
}

public class MyPropertyGridGroup : PropertyGridGroup
{
    private List<PropertyGridItem> items;

    public MyPropertyGridGroup(object key, Group<PropertyGridItem> parent, 
        PropertyGridTableElement propertyGridElement) : base(key, parent, propertyGridElement)
    {
    }

    protected override IList<PropertyGridItem> Items
    {
        get
        {
            if (this.items == null)
            {
                this.items = new List<PropertyGridItem>();
            }

            return this.items;
        }
    }
}

To reproduce:

public Form1()
{
    InitializeComponent();

    this.radPropertyGrid1.SelectedObject = new Item(123, "SampleName");
}

public class Item
{
    public int Id { get; set; }
    public string Name { get; set; }

    public Item(int id, string name)
    {
        this.Id = id;
        this.Name = name;
    }
}

Activate the editor for the "Id" property and click the up arrow of the PropertyGridSpinEditor. Then click on the text box.

Workaround:

private void radPropertyGrid1_EditorInitialized(object sender, PropertyGridItemEditorInitializedEventArgs e)
{
    PropertyGridSpinEditor spinEditor = e.Editor as PropertyGridSpinEditor ;
    if (spinEditor != null)
    {
        BaseSpinEditorElement spinEditorElement = spinEditor.EditorElement as BaseSpinEditorElement;
        var eventInfo = spinEditorElement.TextBoxItem.HostedControl.GetType().GetEvent("MouseEnter");
        var methodInfo = spinEditorElement.TextBoxItem.GetType().GetMethod("TextBoxControl_MouseEnter",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        Delegate handler = Delegate.CreateDelegate(typeof(EventHandler), spinEditorElement.TextBoxItem, methodInfo);
        eventInfo.RemoveEventHandler(spinEditorElement.TextBoxItem.HostedControl, handler);

        var eventInfo2 = spinEditorElement.TextBoxItem.HostedControl.GetType().GetEvent("MouseLeave");
        var methodInfo2 = spinEditorElement.TextBoxItem.GetType().GetMethod("textBoxItem_MouseLeave",
            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
        Delegate handler2 = Delegate.CreateDelegate(typeof(EventHandler), spinEditorElement.TextBoxItem, methodInfo2);
        eventInfo2.RemoveEventHandler(spinEditorElement.TextBoxItem.HostedControl, handler2);
    }
}

To reproduce:
- Add a property grid to a blank form set the selected object the the same form.
- Group the items and click several times to expand collapse the groups or items.
- you will notice that some of expanded/collapsed groups icon is in wrong state (same applies for the +/- sign of the properties).

Here is the code that should be used for custom sub-properties

private void OnCreateItem(object sender, CreatePropertyGridItemEventArgs e)
{
    e.Item = new MyPropertyGridItem((PropertyGridTableElement)sender, e.Parent);
}

As visual studio would be happy of you only provide a constructor with one argument when you inherit from PropertyGridItem you have no way of knowing that you need a second one where the parent should be the second argument.

The proper way to handle this would be to set the parent internally.

To reproduce: use the following code:

Items _items = new Items();

public Form1()
{
    InitializeComponent(); 

    radPropertyGrid1.SelectedObject = _items;
}

class Items
{
    [Description("A Bool Property")]
    public bool IsEnabled
    {
        get
        {
            return _isEnabled;
        }
        set
        {
            _isEnabled = value;
            RadMessageBox.Show("IsEnabled");
        }
    }
    private bool _isEnabled;

    [Description("A String Property")]
    public string Name
    {
        get { return _name; }
        set
        {
            _name = value;
            RadMessageBox.Show("Name");
        }
    }
    private string _name ;

}

Steps to perform:
1. Change the "Name" property and leave the editor active.
2. Click on the check box to change the "IsEnabled" property.

As a result you will notice that the "IsEnabled" setter is called before the "Name" setter.

Workaround:

Items _items = new Items();

public Form1()
{
    InitializeComponent(); 

    this.radPropertyGrid1.CreateItemElement += radPropertyGrid1_CreateItemElement;        
    radPropertyGrid1.SelectedObject = _items;
}

private void radPropertyGrid1_CreateItemElement(object sender, CreatePropertyGridItemElementEventArgs e)
{
    if (e.ItemElementType == typeof(PropertyGridCheckBoxItemElement))
    {
        e.ItemElementType = typeof(CustomPropertyGridCheckBoxItemElement);
    }
}

public class CustomPropertyGridCheckBoxItemElement : PropertyGridCheckBoxItemElement
{
    public CustomPropertyGridCheckBoxItemElement()
    {
        this.CheckBoxElement.ToggleStateChanging += CheckBoxElement_ToggleStateChanging;
    }

    private void CheckBoxElement_ToggleStateChanging(object sender, StateChangingEventArgs args)
    {
        if (this.PropertyTableElement.ActiveEditor != null && this.PropertyTableElement.SelectedGridItem != this.Data)
        {
            this.PropertyTableElement.EndEdit();
        }
    }

    protected override void DisposeManagedResources()
    {
        this.CheckBoxElement.ToggleStateChanging -= CheckBoxElement_ToggleStateChanging;

        base.DisposeManagedResources();
    }
}

To reproduce:
- Add 20 document windows that contain property grid to a dock (use RadTextBox for he grid's selected object).
- Close and dispose the windows.
- The memory is not properly released.

To reproduce:

Set the following object as selected of RadPropertyGrid: 

class TestClass : System.ComponentModel.INotifyPropertyChanged
{
    private string loggingType = "0";

    [TypeConverter(typeof(CustomListConverter)), CategoryAttribute("Logging Settings")]
    public string LoggingType
    {
        get { return loggingType; }
        set
        {
            loggingType = value;
            OnPropertyChanged("LoggingType");
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public virtual void OnPropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

}

And use the following converter:

public class CustomListConverter : System.ComponentModel.StringConverter
{
    ArrayList _AllStringValues = new ArrayList();
    Hashtable _Map = new Hashtable();

    public CustomListConverter()
    {
    }

    public override System.ComponentModel.TypeConverter.StandardValuesCollection GetStandardValues(ITypeDescriptorContext conte
    {
        FillValuesFromContext();
        StandardValuesCollection standardValues = new StandardValuesCollection(_AllStringValues);
        return standardValues;
    }

    private void FillValuesFromContext()
    {
        if (_AllStringValues.Count > 0)
            return;

        _AllStringValues.Clear();
        _Map.Clear();

        string str = "-5,Fatal|-4,Error|-3,Warning|-2, Info|-1,Debug|0,Trace";

        string[] strMapVals = str.Split('|');
        for (int i = 0; i < strMapVals.Length; i++)
        {
            string[] strVals = strMapVals[i].Split(',');
            if (strVals.Length != 2)
                continue;

            _AllStringValues.Add(strVals[0].Trim());
            _Map.Add(strVals[0].Trim(), strVals[1].Trim());
        }
    }

    public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
    {
        FillValuesFromContext();

        string displayString = "";

        IEnumerator enumTable = _Map.Keys.GetEnumerator();

        while (enumTable.MoveNext())
        {
            if (_Map[enumTable.Current] as string == value as string)
            {
                displayString = enumTable.Current as string;
                break;
            }
        }

        return displayString;
    }

    public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
    {
        FillValuesFromContext();

        if (null != value && _Map.ContainsKey(value.ToString()))
        {
            return _Map[value];
        }

        return value;
    }

    public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
    {
        return true;
    }

    public override bool GetStandardValuesExclusive(ITypeDescriptorContext context)
    {
        return true;
    }
}

When you start the application you will see that the value of the property is set to -1, while it should be converted to 'Debug'

Workaround:

Create a custom PropertyGridItem:

public class MyPropertyGridItem : PropertyGridItem
{
    public MyPropertyGridItem(PropertyGridTableElement element)
        : base(element)
    {
    }

    public override string FormattedValue
    {
        get
        {
            string baseFormattedValue =  base.FormattedValue;
            TypeConverter converter = TypeConverter;

            if (converter != null && converter.CanConvertTo(this, typeof(string)))
            {
                baseFormattedValue = converter.ConvertToString(this, System.Threading.Thread.CurrentThread.CurrentCulture, this.Value);
            }

            return baseFormattedValue;
        }
        set
        {
            base.FormattedValue = value;
        }
    }
}

Use it by subscribing to the CreateItem event:

void radPropertyGrid1_CreateItem(object sender, Telerik.WinControls.UI.CreatePropertyGridItemEventArgs e)
{
    e.Item = new MyPropertyGridItem(this.radPropertyGrid1.PropertyGridElement.PropertyTableElement);
}

Workaround: 

  class MyRadPropertyGrid : RadPropertyGrid
    {
        protected override void WndProc(ref Message m)
        {
            switch (m.Msg)
            {
                case 0x7b:
                    Point point;
                    int x = Telerik.WinControls.NativeMethods.Util.SignedLOWORD(m.LParam);
                    int y = Telerik.WinControls.NativeMethods.Util.SignedHIWORD(m.LParam);
                    if (((int)((long)m.LParam)) == -1)
                    {
                        point = new Point(this.Width / 2, this.Height / 2);
                    }
                    else
                    {
                        point = this.PointToClient(new Point(x, y));
                    }

                    this.PropertyGridElement.PropertyTableElement.ProcessContextMenu(point);
                    return;
            }

            base.WndProc(ref m);
        }
    }

If one sets an empty RadPropertyStore to the SelectedObject property of a RadPropertyGrid and then adds items with a RadSortOrder attribute the items will still be sorted by their name.



WORKAROUNDS:

1. Populate the store before you set it to the property grid.

2. Add a dummy item to the store before you set it to the property grid and then remove it:
RadPropertyStore store = new RadPropertyStore();
store.Add(typeof(bool), "dummy", false);
this.radPropertyGrid1.SelectedObject = store;
store.RemoveAt(0);

3. After you add the first item to the store call the following method:
this.radPropertyGrid1.PropertyGridElement.PropertyTableElement.ListSource.CollectionView.EnsureDescriptors();