To reproduce:
public RadForm1()
{
    InitializeComponent();
    var a = new Author(null, "John");
    for (int i = 0; i < 20; i++)
    {
        radChat1.AddMessage(new ChatTextMessage("Item" + i, a, DateTime.Now.AddDays(-(20 - i))));
    }
    new Telerik.WinControls.RadControlSpy.RadControlSpyForm().Show();

    this.radChat1.ChatElement.MessagesViewElement.TimeSeparatorInterval = TimeSpan.FromDays(1);
}

You will notice that there is today in several places. 

Workaround:
this.radChat1.ChatElement.MessagesViewElement.TimeSeparatorInterval = TimeSpan.Zero;

var a = new Author(null, "Forest Gump");
for (int i = 0; i < 20; i++)
{
    radChat1.AddMessage(new ChatTextMessage("Item" + i, a, DateTime.Now.AddDays(-(20 - i))));

    ChatTimeSeparatorDataItem separator = new ChatTimeSeparatorDataItem(new ChatTimeSeparatorMessage(DateTime.Now.AddDays(-(20 - i))));
    radChat1.ChatElement.MessagesViewElement.Items.Add(separator);
}

Note: other operations that affect the image's size should also handle large images.

No Workaround.

It is possible to create a custom resize dialog as follows:
        public class MyRadImageEditor : RadImageEditor
        {
            protected override RadImageEditorElement CreateImageEditorElement()
            {
                return new MyRadImageEditorElement();
            }
        }

        public class MyRadImageEditorElement : RadImageEditorElement
        {
            public override void ShowResizeDialog()
            {
                this.ShowDialog(typeof(MyResizeDialog));
            }
        }

        public class MyResizeDialog : RadForm
        {
            public MyResizeDialog(RadImageEditorElement imageEditorElement)  
            {
               
            }

            //TODO custom dialog
        }

How to reproduce: 
1. Use the following code to change the default style of the document:
StyleDefinition h2 = this.radRichTextBox.Document.Style;
h2.SpanProperties.FontFamily = new System.Windows.Media.FontFamily("Microsoft Sans Serif");
h2.SpanProperties.FontSize = Unit.PointToDip(8.25f);
h2.ParagraphProperties.SpacingAfter = 0;

h2 = radRichTextBox.Document.Style;
h2.SpanProperties.FontFamily = new System.Windows.Media.FontFamily("Microsoft Sans Serif");
h2.SpanProperties.FontSize = Unit.PointToDip(8.25f);
h2.ParagraphProperties.SpacingAfter = 0;

StyleDefinition hyperlinkStyle = this.radRichTextBox.Document.StyleRepository["Hyperlink"];
hyperlinkStyle.SpanProperties.FontFamily = new System.Windows.Media.FontFamily("Microsoft Sans Serif");
hyperlinkStyle.SpanProperties.FontSize = Unit.PointToDip(8.25f);

2. Add some text to the document

3. Add a hyperlink somewhere in the middle of the text

4. Start moving the caret so it moves over the hyperlink start

Observed: When on hyperlink start/end, the caret is with bigger size than the content

Expected: The caret should be with the size of the content

How to reproduce:
this.radTrackBar1.LabelStyle = Telerik.WinControls.UI.TrackBarLabelStyle.TopLeft;
this.radTrackBar1.TickStyle = Telerik.WinControls.Enumerations.TickStyles.TopLeft;

Workaround:
this.radTrackBar1.LabelStyle = Telerik.WinControls.UI.TrackBarLabelStyle.TopLeft;
this.radTrackBar1.TrackBarElement.BodyElement.ScaleContainerElement.BottomScaleElement.Visibility = ElementVisibility.Collapsed;

To reproduce:
- Add RadLayoutControl to a form.
- Change the Language property at design time.
- You will receive the following message: There is already a command handler for the menu command '1496a755-94de-11d0-8c3f-00c04fc2aae2 : 103'. 

Workaround:
- Reopen the designer.

Workaround: create the ThemableColor this way

SetBordersCommandParameter bordersParam = new SetBordersCommandParameter();
System.Drawing.Color color = Color.Blue;
System.Windows.Media.Color mediaColor = System.Windows.Media.Color.FromArgb(color.A, color.R, color.G, color.B);
bordersParam.BorderColor = new ThemableColor(mediaColor);

To reproduce:
- Open the Element Hierarchy Editor and resize it.

How to reproduce: enabled High DPI scaling and create a form as an MDI child with a RadDataEntry control in it
Workaround:  handle the Shown event of the MDI child and manually perform the scaling
private void radButtonElement1_Click(object sender, EventArgs e)
        {
            var view = new RadForm1
            {
                MdiParent = this
            };
            
            view.Shown += View_Shown;
            view.Show();
        }

        private void ScaleRadControls(Control c)
        {
            foreach (var item in c.Controls)
            {
                Control control = item as Control;
                if (control == null)
                {
                    continue;
                }

                this.mi.Invoke(control, new object[] { this.FormElement.DpiScaleFactor, BoundsSpecified.All });
                ScaleRadControls(control);
            }
        }

        MethodInfo mi;
        private void View_Shown(object sender, EventArgs e)
        {
            this.mi = typeof(Control).GetMethod("ScaleControl", BindingFlags.Instance | BindingFlags.NonPublic, null, new Type[] { typeof(SizeF), typeof(BoundsSpecified) }, null);
            RadForm1 v = sender as RadForm1;
            if (v != null)
            {
                ScaleRadControls(v.radDataEntry1.PanelContainer);
            }
        }

One should be able to persist to a file all changes made when using the element hierarchy editor at design time.

It will be nice if one can add his custom sub menu items at design-time through the 'Add new item' menu. This was supported in the past, but the support was removed together with the introduced design-time optimizations.

Currently the sgen tool raises an exception when executing it on RadControls and RadControls.UI. There is also an XmlSerialization exception when  loading the application.

One should be able to export to a stream instead to a file as well.

To reproduce:
- Drag RadDropDownList control on a form, expand its DropDownListElement property, and change the ItemHeight
- Another case is, on a RadForm, expand FormElement>TitleBarElement and set its Visibility to Collapsed

Workaround: set the desired property at runtime
radDropDownList1.DropDownListElement.ItemHeight = 22;

Steps to reproduce:
1. Drag a grid on the form
2. Drag one or more controls over the grid - at this point in the Document Outline you can see the dragged control is a child of the grid
3. Open the Property Builder of the grid and close it - at this point the dragged control disappears

Workaround:
1. Open the Designer.cs file, and locate the line, where the control is added to the grid e.g.
            this.radGridView2.Controls.Add(this.radButton4);
and change it to:
            this.Controls.Add(this.radButton4);

If need be, set the Location property of the control at design time, to position it at the desired place.

2. Alternatively, you can place the control outside the grid bounds and after selecting it, use the arrow keys to position is over the grid. This will not make it its child, hence the issue will not appear.

To reproduce:

Create a RadForm and add a RadButton. Open the Element Hierarachy Editor and set the ShowBorder of the RadButtonElement to false. Another way is to set the ShowBorder property through the Properties section in Visual Studio. Save the form, close it and reopen it. You will see that the border is shown  and the property is set to true.

Workaround:

Set the value at runtime:

this.radButton1.ButtonElement.ShowBorder = false;