The approach as per the following documentation article is not working: https://docs.telerik.com/devtools/winforms/controls/richtexteditor/features/custom-fonts

To reproduce: run the Demo application >> RichTextEditor >> First Look example and follow the steps illustrated in the attached gif file. 

1. First add a footnote in the text
2. Than select a part of the footnote text or all text and use the context menu to cut the text
3. Then,  paste the text in the document, it doesn't matter were.
4. Next step is to remove the footnote reference.
5.Then, scroll through the document and press the right mouse button to open the context menu.

The object release should have been called and the context menu is disposed. If so the error occurs.

Workaround:

this.radRichTextEditor1.MouseClick += radRichTextEditor1_MouseClick;

        private void radRichTextEditor1_MouseClick(object sender, MouseEventArgs e)
        {
            if (e.Button == System.Windows.Forms.MouseButtons.Right)
            {
                if (this.radRichTextEditor1.RichTextBoxElement.ContextMenu != null)
                {
                    FieldInfo fi = typeof(Telerik.WinControls.RichTextEditor.UI.ContextMenu).GetField("radDropDownMenu", BindingFlags.Instance | BindingFlags.NonPublic);
                    RadDropDownMenu dropdown = fi.GetValue(this.radRichTextEditor1.RichTextBoxElement.ContextMenu) as RadDropDownMenu;
                    if (dropdown.IsDisposed)
                    {
                        this.radRichTextEditor1.RichTextBoxElement.ContextMenu = new Telerik.WinControls.RichTextEditor.UI.ContextMenu();
                    }
                }
            }
        }

The issue only reproduces on Windows 10( 1806). Check the attached video showing the result: 

Workaround: Handle the CommandExecuting event this way
private void RadRichTextEditor1_CommandExecuting(object sender, Telerik.WinForms.Documents.RichTextBoxCommands.CommandExecutingEventArgs e)
{
    if (e.Command is ChangeFontFamilyCommand && e.CommandParameter.ToString() == "")
    {
        e.Cancel = true; 
    }
}

To reproduce:
- Click the AA Styles button to open the Styles dialog.
- Scroll down and select the CodeBlock item
- The style does not change


 

Importing html documents having the property vertical-align property used with length values - for example: vertical-align = 3px, throws InvalidCastException. 

This field retrieves a character through a code value specified in the field-argument. Such documents are common and are created when symbols (e.g. with font Windings through Insert -> Symbol dialog) are inserted in RTF documents in MS Word.

To reproduce: 
var d = new RadDocument();
var s = d.GetStatisticsInfo();

Workaround:
var d = new RadDocument();

if (d.Sections.Count > 0 && d.Sections.Last.Blocks.Count >0)
{
    var s = d.GetStatisticsInfo();
}  

When the document is protected, CommandExecuting is not raised when the user double clicks the header or footer area.

I added this line just before Application.Run(new MainForm()); in Word-inspired project:

 

I took RichTextBoxStrings.xml from localization page of RichTextEditor. In the xml file I converted all the text between <value> tags to uppercase, and also replaced "OK" (value of "Confirm" data element) with "AYE". I expected all the OK's in all the forms within rich text editor to be replaced, but they all remained as "Ok" (note the lower case "k" here). Well, all except Page Layout > Columns form, which did display AYE, and also References > Insert citation. So, here are the issues that I found:

• XML file in localizaiton page of RichTextEditor is missing entries for resources "Ok", "Insert", and "Apply".
• "Ok" resource is used in most places, but "Confirm" resource (with value "OK") is used in AddNewBibliographicSourceDialog.cs and SectionColumns\SectionColumnsDialog.cs. This seems inconsistent.
• Paper sizes are not localizable, which is actually fine by me for all but the last paper size, "Size14x10", but then what is the purpose of all RibbonUI_PaperSizeXxx resources in resource file?
• Value of resource "Documents_InsertHyperlinkDialog_SelectionInDocument" is weird. Not sure this resource should even exist, as I could not make it appear in the InsertHyperlinkDialog. Looks like a dummy placeholder.
• Fallback mechanism for missing resources is weird. If resource is missing the resource name is returned as resource value, which is the reason why Ok, Insert, and Apply are actually shown. Maybe this is intentional, if resource is missing it will be obvious (for unusual resource names). Alternative would be not to change the string at all, as it is already set to default english in .Designer.cs file anyway. So instead of "this.someTextBox.Text = LocalizationManager.GetString("Some_Resource");" it would be something like "this.someTextBox.Text = LocalizationManager.GetString("Some_Resource", this.someTextBox.Text);".

To create AllCapsRichTextBoxStrings.xml, make a copy of provided resource file, open it in Notepad++ and replace all <value>([^<]*)</value> with <value>\U\1\E</value> using regular expressions, and then replace all &AMP;, &LT; and &GT; with &amp;, &lt; and &gt;.

If we open paragraph properties dialog and then Tabstops properties dialog, and then close the second one the first one will also close automatically.

RadRichTextEditor: MoveToDocumentElementStart works incorrectly when called consecutively with PermissionRangeStart as parameter
When the MoveToDocumentElementStart is called with parameter that is PermissionRangeStart and then is called a second time, the position moves to the previous position instead.

Currently invalid attribute values, including invalid or empty values in CSS attributes in the 'style' attribute, could cause importing property with incorrect value, or NullReferenceException (the document cannot be imported).
Examples:
----------------------------------------------------------
<table width=”*”>
	<tr>
		<td>More Random Text</td>
	</tr>
</table>

The table is imported with 0 width. Instead the width should not be set.
----------------------------------------------------------
<table style="font-size:;">
	<tr>
		<td>More Random Text</td>
	</tr>
</table>

NullReferenceException is thrown.
----------------------------------------------------------
<p style='padding: 3px 3px 3xp 7px;'>test</p>

IndexOutOfRangeException is thrown.

----------------------------------------------------------
 

Workaround: replace the invalid values before import:
string importString = html.Replace("font-style: ;", "");

The field result shows the number of pages the current section contains.

See attached!

The spacing between the letters is too big.