When navigating inside a table in the RadEditor, pressing the right arrow key of the keyboard moves the cursor only till the last table cell and the cursor does not exits the table. 

The Insert Web Part tool in RadEditor for SP 2010 throws JavaScript error (reproducible in all browsers).

Steps to reproduce:
1. Open http://sharepoint.telerik.com/aspnet-ajax/web-parts/Pages/Content-Editor-Web-Part-using-RadEditor.aspx
2. Click over the content of the Editor, so the toolbar will be shown
3. Click over the Insert Web Part Tool

video - http://screencast.com/t/Df3aV6svUy

RadEditor's content is messing up when links are generated through document manager and submit it from Preview mode. The issue is reproducible in Internet Explorer 7

However, a possible workaround for the issue would be to set the following code the OnClientSubmit event of the RadEditor:

<telerik:RadEditor OnClientSubmit = "OnClientSubmit" />
 
<script>
   function OnClientSubmit(editor)
   {
   editor.set_mode(1); //Force design mode
   }
</script>

When opening a RadEditor under Chrome and switch to HTML mode in the bottom left corner, close to the Design title there is missing a small part of the border.

Telerik version 2011.1.614.35
I am facing following two issues with RadEditor on Chrome (version 28.0.1500.95) and Safari (version 5.1.7) -

a. Gray area is seen in the lower part of the RadEditor for Design and Preview modes. When some text is typed, the gray background vanishes for that line of text. 

b. Border of the RadEditor is not complete at the bottom left corner in the HTML mode. This behavior is seen whenever there is some text in it, be it the default text or the text of the field that is bound. 

Please refer the attachment RadEditorIssues.png 

Ability for the RadEditor's validator dialog to validate HTML 5 markup inside it's content

A possible workaround:
<rad:RadEditor ID="RadEditor1" runat="server" OnClientCommandExecuted="OnClientCommandExecuted"></rad:RadEditor>
function OnClientCommandExecuted(editor, args) {
                if ("Unlink" == args.get_commandName()) {
                    if ($telerik.isFirefox) {
                        var anchor = editor.getSelectedElement();
                        if (anchor && anchor.nodeName == "A") {
                            Telerik.Web.UI.Editor.Utils.removeNode(anchor);
                        }
                    }
                }
            }  

When hyperlinks are inserted into the content of RadEditor in preview mode there are additional attributes , which are retrieved by the get_html() method. 

If the MaxHtmlLength is set and the content is close to the limit on switching to preview mode breaks the normal behavior of the editor. The validator alerts that the length is exceeded, because of the additional attributes and the client is not able to open any other mode.

AutoResizeHeight functionality is not working correctly under IE, Chrome and Opera, when it is set to true.

Behavior:
Under IE: Editor is not resized when content is deleted.
Under Chrome: Editor's content area is resized to cover the space but the editor preserve its height.
under Opera: Editor keeps expanding when removing content.

 If there are textarea tags or style tags in the HTML content of RadEditor, after completing the spell check  the content is repeated several times. 

The Bold, Italic, Underline, Subscript and Superscript commands do not work in a combination with EnableTrackChanges="true" and ToolbarMode="RibbonBar".

RadEditor uses a RadWindow for its dialogs so when the global rendering of RadCocntrols on the page is set to Lightweight the dialogs need to be consistent.
There could be implemented a property to control the RenderMode of the dialogs themselves.

When the property 'AutoResizeHeight' is set to 'true' and 'ContentAreaMode' is set to 'Div', the appearance of RadEditor will be distorted in IE10. Also, the height of the editor is reduced the first time HTML view is selected under IE10 and older versions when the same setup is used.

To replicate this (as it is rather difficult to explain) go to http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
Click on the HTML tab and replace all the content with:

<div>
  <div>
    <div style="width: 100%;">foo bar
    </div>
  </div>
</div>

Click back on the Design tab and click at then end of the first line.  When you press enter, the new line will be filled with non breaking spaces equal to the amount the inner-most div was indented.

When creating links in RadEditor if the href attribute has square brackets, opening the hyperlink manager will appear like there is no url at all. 
If OK button is clicked the url disappears.

When the Editor is used in Right to Left mode, the modules at the bottom of the control are not properly positioned and the resizing handler does not point to the right direction - http://screencast.com/t/JwPlpE3zPDzi

The value set to the EmptyMessage of the editor floats outside the EDitor if its length exceeds the Editor's width - http://screencast.com/t/rPLVwFVfU

The error is Sys.InvalidOperationException: Sys.InvalidOperationException: Component 'RadEditor1_dialogOpener' was not found.

When not enabled RadEditor should merely show its content, when Enabled is toggled to true it should render toolbars and add its functionality.

A possible workaround is using the Visible property instead and a div with runat=server as a placeholder for the editor while it is not rendered (its Content property will still return the HTML in it). Thus, the innerHTML server property of the div can be used to set the HTML from RadEditor in it.

RadEditor's height is increasing as the content increases in iPad. The height of the control should remain the same but scrollbars should be displayed in the content area.