It is a common scenario users to start selecting text and accidental trigger mouseup event outside of the content area. Still, the focus is inside RadEditor and InlineEditCompleted event should not fire.

Possible workaround:

<telerik:RadEditor runat="server" ID="RadEditor1" EditType="Inline"
    OnClientLoad="OnClientLoad" OnClientInlineEditCompleted="OnClientInlineEditCompleted">
    <Content>
       some text
    </Content>
</telerik:RadEditor>

<script>
    function OnClientInlineEditCompleted(sender, args) {
        if (sender._editCompleted) {
            alert("Fired!");
        }
    }

    function OnClientLoad(sender, args) {
        $telerik.$(document).on("mouseup", function (e) {
            if (e.target === sender.get_contentArea() || e.target === sender.get_textArea()) {
                sender._editCompleted = true;
            }
        })

        $telerik.$(document).on("mousedown", function (e) {
            if (e.target === sender.get_contentArea() || e.target === sender.get_textArea()) {
                sender._editCompleted = false;
            } else {
                sender._editCompleted = true;
            }
        })
    }
</script>

The exact steps to reproduce are:

1. Use RadEditor in http://localdemos.telerik.com/aspnet-ajax-dev/editor/examples/overview/defaultcs.aspx
2. Add this HTML:
        <p>start</p>
        <p>&nbsp;</p>
        <p>end</p>

3. Go to Design;
4. Select from the empty paragraph (<p>&nbsp;</p>) to the end of text (<p>end</p>);
5. Copy via Ctrl+C;
6. Try to paste at the end of the "end" paragraph.

You can workaround this issue by using this override:

<telerik:RadEditor runat="server" ID="RadEditor1">
    <Content>
        <br/>
        <iframe src="about:blank">Iframe not supported</iframe>
    </Content>
</telerik:RadEditor>

<script>
    Telerik.Web.UI.Editor.Utils._copyElementsBetweenNodes = function (oldNode, newNode, elementName)
    {
        var oldElements = oldNode.getElementsByTagName(elementName);
        var newElements = newNode.getElementsByTagName(elementName);
        for (var i = 0; i < oldElements.length; i++)
        {
            switch (elementName)
            {
                case "script":
                case "title":
                    newElements[i].text = oldElements[i].text;
                    break;
                case "style":
                    if (newElements[i].innerHTML != oldElements[i].innerHTML)
                    {
                        newElements[i].styleSheet.cssText = oldElements[i].styleSheet.cssText;
                    }
                    break;
                case "select":
                    newElements[i].selectedIndex = oldElements[i].selectedIndex;
                    break;
                case "input":
                    if ((oldElements[i].type == 'radio' || oldElements[i].type == 'checkbox') && $telerik.$(oldElements[i]).attr("checked"))
                    {
                        $telerik.$(newElements[i]).attr("checked", "checked");
                        if ($telerik.isIE9Mode && oldElements[i].type == 'checkbox' && oldElements[i].checked)
                        {
                            newElements[i].checked = true;
                            newElements[i].setAttribute("checked", "checked");
                        }
                    }
                    break;
                case "iframe":
                    var innerHTML = oldElements[i].innerHTML;
                    if (innerHTML)
                    {
                        var outerHTML = newElements[i].outerHTML;
                        if (outerHTML)
                        {
                            var gtIndex = outerHTML.indexOf(">");
                            if (gtIndex > 0)
                            {
                                outerHTML = outerHTML.substr(0, gtIndex) + ">" + innerHTML + outerHTML.substr(gtIndex + 1 + innerHTML.length);
                                newElements[i].outerHTML = outerHTML;
                            }
                        }
                    }
                    break;
                default:
                    if (newElements[i].innerHTML != oldElements[i].innerHTML)
                        $E.Utils.setElementInnerHtml(newElements[i], oldElements[i].innerHTML);
                    break;
            }
        }
    };
</script>

For example, using this markup:

<telerik:RadEditor ID="RadEditor1" runat="server" ToolbarMode="RibbonBar">
</telerik:RadEditor>

and this Page_Init code:

protected void Page_Init(object sender, EventArgs e)
{
    RadEditor1.RenderMode = RenderMode.Lightweight;
}

Causes icons to either miss or their position is incorrect.

It becomes the operation of Chrome only.

after the new line, if you type continuously double-byte character string "あい",the input result was "い".
The correct answer is "あい".

For operation that does not occur in earlier versions, I think I've considered this release version of the bug, the cause can be identified?

The Paste event is added twice to the Editor's undo stack in IE. The issue is reproducible as of Q3 2013.

Steps to reproduce:
1. Open http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
2. Paste some content

Result: The Paste command is added two time in the Undo stack

The content is not scrolled to the end of the pasted content in IE11 - the scrollbar keeps its initial position instead. The issue is reproducible in IE (tested in IE11) and Chrome, but not in Firefox nor standard editable iframe.

Steps to reproduce:
1. Open in IE: http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
2. Paste big enough content, so the scrollbar will be shown

Actual: The scrollbar stays on the top.
Expected: The content area is scrolled to the end of the pasted content

Possible workaround could be creating a temporary selectable element after the pasted content, which to be selected manually:
		<telerik:RadEditor ID="txtMessage"  runat="server" OnClientPasteHtml="OnClientPasteHtml">
		</telerik:RadEditor>
		<script>
			function OnClientPasteHtml(editor, args) {
				if (args.get_commandName() == "Paste" && $telerik.isIE) {
					args.set_value(args.get_value() + "<div id='selectableEl'></div>");
					setTimeout(function () {
						var selectedEl = editor.get_document().getElementById("selectableEl");
						console.log(editor.getSelectedElement());
						Telerik.Web.UI.Editor.Utils.scrollTo(selectedEl, editor);
						$telerik.$(selectedEl).remove();
					}, 0);
				}
			}
		</script>

In scenarios where RadEditor is moved through the DOM the typical approach is to call the onParentNodeChanged method in order to re-render the editor. In Edge browser this does not work. CleanAtributes filter is alerted as failed and further RadEditor is unresponsive. 

Temporary solution is to switch the content area mode to DIV:

     <telerik:RadEditor ID="RadEditor1" runat="server" ContentAreaMode="Div" />

Using plain RadEditor controls with default Default toolbar where ToolProvideID is also used, a JS error is thrown and ToolProvide mechanism does not operate as expected. 

As a temporary workaround, you can use any other toolbar mode (e.g., ShowOnFocus).

When having a video object added via the Media Manager, switching from Design to HTML couple of times results to multiple param tags duplicated. 

Tracked content that is deleted should be removed directly, but newly added content should be tracked.

Setting render mode to auto or lightweight via the web.config does not affect the rendering of RadEditor with markup that is used with FileManager's composite properties. For example, ImageManager-MaxUploadFileSize, ImageManager-ViewPaths, etc. 


For the time being, you can explicitly set the RenderMode property of RadEditor to either Auto or Lightweight in order to resolve the problem. 

When resizing images in RadEditor design mode using the corner-handles the image should retain its aspect ratio. This works very good in Firefox (v. 41.0.2) out-of-the-box because the browser implements that functionality but not in IE (v. 11.0) or Chrome (46.0) in Windows 8.1 (v 6.3, build 9600).

FileBrowser dialogs cannot upload files greater than 200kb when AsyncUpload is disabled (i.e., the Upload control is used instead). 

ColorPicker inside a RadEditor don't fit inside DropDownBody, the last color jumps down a row. This happens when RadEditor Skin is set MetroTouch and RenderMode to Lightweight.
Video: http://screencast.com/t/4GOnnf0UcsfU

The RadEditor is posting multiple symbols when you select to insert a symbol. This happen when the RenderMode is set to LightWeight. The problem is reproducible also when inserting code snippets via the "Insert Code snippet" tool.
video - http://screencast.com/t/DfBMWrW4Px7I

Steps to reproduce:
1. Open http://demos.telerik.com/aspnet-ajax/editor/examples/rendermodes/defaultcs.aspx
2. Try to insert a symbol through "Insert Symbol" command
    Result: Two symbols are inserted instead of one

Did telerik rich text editor check arabic language with the spell checker ?