When ToolbarMode is set to "RibbonBarFloating" the RadEditor height becomes greater than the control height. As a result the wrapper overlaps with the elements box below.

As a temporary workaround for ToolbarMode="RibbonBarFloating" only, the following JavaScript code need to be applied on the page:

   <script type="text/javascript">
            (function () {
                var getToolbarHeight = Telerik.Web.UI.Editor.UI.DimensionsCalculator.prototype._getToolbarHeight;
                Telerik.Web.UI.Editor.UI.DimensionsCalculator.prototype._getToolbarHeight = function (container) {
                    var $container = $telerik.$(container);
                    $container.append($container.find("div"));
                    return getToolbarHeight.call(this, container);
                }
            })();
</script>

The issue is reproducible when NewLineMode is Br and the cursor is at the end of the formatting node in Chrome. 

The workaround is to check the position of the new inserted Br element and append it to the formatting node if it is necessary.

<telerik:RadEditor ID="RadEditor1" runat="server" NewLineMode="Br">
</telerik:RadEditor>

<script type="text/javascript">
	(function () {
		if (!$telerik.isChrome)
			return;
		var insertBr = Telerik.Web.UI.Editor.EnterNewLineCommand.prototype._insertBrElementSafari;
		Telerik.Web.UI.Editor.EnterNewLineCommand.prototype._insertBrElementSafari = function () {
			var utils = Telerik.Web.UI.Editor.Utils,
				command = this,
				selection = command.get_editor().getSelection(),
				range = selection.getRange();

			if (range.commonAncestorContainer != range.startContainer || range.commonAncestorContainer != range.endContainer)
				return insertBr.call(command);

			var commonElement = utils.isTextNode(range.commonAncestorContainer) ?
				range.commonAncestorContainer.parentNode : range.commonAncestorContainer;

			var commandResult = insertBr.call(command);
			range = selection.getRange();
			var br = range.commonAncestorContainer.childNodes[range.startOffset];

			if (!utils.isTag(br, "br"))
				return commandResult;

			if (!$telerik.$.contains(commonElement, br)) {
				commonElement.appendChild(br);
				range.selectNodeContents(commonElement);
				range.collapse(false);
				selection.selectRange(range);
			}

			return commandResult;
		}
	})();
</script>

Steps:
1. Add some track changes text using Author=User0 and UserCSSId="reU0".
2. Change the Author to "User1" and UserCSSId to "reU1". 
3. Click inside of User0's tracked text and start typing.

Results: The new text is displayed as if User0 wrote it, in User0's color.

Expected Result: The new text that was injected by User1 in the middle of User0's text would be have User1's color and hover text that pertains to User1. (Similar to how Word does it.)

When there are list items which are links, pressing enter to create new list item duplicates the previously created anchor.

The same issue applies when new lines are created with link inside.

Spell Checking throws JS error on a subsequent opening of the spell checking dialog. 

You can resolve this by forcing the IE11 browser to IE10 compatibility mode.

<meta http-equiv="X-UA-Compatible" content="IE=10" />

When using the built-in AJAX Spell Checker of the Editor, on the first misspelled word the corresponding popup opens. 

When the user finishes with the first word, the same popup should open for the following word, but under IE11 this does not happen and the user is forced to click on the word for the dialog to open.

To resolve this you can force the IE11 browser to IE10 compatibility mode with a meta tag in the head element pf the page

<meta http-equiv="X-UA-Compatible" content="IE=10" />

The floating toolbar window does not open when the user toggles to full screen.

You can resolve the issue by incorporating the following script block:

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

<script type="text/javascript">
    Telerik.Web.UI.Editor.DefaultToolAdapter.prototype._showToolbarHolder = function (isVisible) {
        var editor = this.get_editor();
        var toolbarEnum = Telerik.Web.UI.EditorToolbarMode;
        if (!isVisible) {
            if (this._toolbarHolder) this._toolbarHolder.hide(); //NEW - Add a check for the toolbar holder
            return;
        }
        
        //Hide if in fullscreen mode and toolbar is ShowOnFocus
        if (editor.isFullScreen() && editor.get_toolbarMode() === Telerik.Web.UI.EditorToolbarMode.ShowOnFocus ) return;

        //Hide previous wrapper and mark yourself as the wrapper
        var wrapper = Telerik.Web.UI.Editor.DefaultToolAdapter._visibleWrapper;

        //Return if you are already visible
        if (wrapper == this && wrapper._toolbarHolder && wrapper._toolbarHolder.isVisible())//NEW - toolbar holder might not be created!
        {
            //Activete it before returning, as it could have been deactivated after showing an editor dialog
            wrapper.get_toolbarHolder().setActive(true);
            return;
        }

        if (wrapper && wrapper._showToolbarHolder) wrapper._showToolbarHolder(false);
        Telerik.Web.UI.Editor.DefaultToolAdapter._visibleWrapper = this;

        //Create the holder in the last possible moment before showing
        this.get_window();

        //Do additional initialization depending on toolbar mode
        this._initNonDefaultToolbarMode();

        //Show toolbar hodler
        this._toolbarHolder.show();

        //IE, ShowOnFocus, PageTop: hide properly the fake toolbar parent here instead _moveToolbarsToEditor
        if ($telerik.isIE) {
            var toolbarMode = editor.get_toolbarMode();
            switch (toolbarMode) {
                case toolbarEnum.ShowOnFocus:
                case toolbarEnum.PageTop:
                    editor.get_TopZone().firstChild.style.display = "none";
                    break;
            }
        }
    };
</script>

Such tools exist in Word 2013 - 'Show Markup' and 'Display for Review' tools.

They are used by the users to be able to see the originally typed text, the final results (as if the track changes were accepted) and some further options for the visual appearance of the tracked text.

Such option would be very useful in the RadEditor, because in a large text where multiple users would add their suggestion, redaction and comments, the text would go quite unordered and difficult to be handled with. 

Clipboard operations are restricted in these browsers and when the paste tool is used nothing is happening. An alert should show up just like the Copy and Cut tools are designed.

A possible workaround is using the same functionality as the Cut command by incorporating the following JavaScript line of code

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

 <script type="text/javascript">
 	Telerik.Web.UI.Editor.CommandList["Paste"] = Telerik.Web.UI.Editor.CommandList["Cut"];
</script>

When typing text, user tries to change the font-size or font-name a span element is added into the content with the chosen formatting options, but new text is not added into the span but outside.

Due to that the applied formatting does not affect the new text typed in the RadEditor. 

When a BR tag has no precedent text, it is automatically removed. This causes issues when user wants to add some space between lines in the content.

For the time being you can use the ContentAreaMode="Iframe" mode as an alternative solution.

The native ASP.NET controls are capable to preserve their values when using back button of the browser. In the RadEditor control this appears to be broken since 2014 Q1. 

This issue is encountered due to bug fixing related to a memory leak in IE8. You can resolve this by using the old functionality for content preserving and verify if everything works as expected under IE8.

The following markup example shows how to roll back to the old behavior:

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

<script>
    Telerik.Web.UI.RadEditor.prototype.set_contentHiddenTextareaValue = function (htmlValue) {
        var utils = Telerik.Web.UI.Editor.Utils;
        $telerik.$(this._contentHiddenTextarea).val(utils.encodePostbackContent(htmlValue));
    };
</script>

This matter causes incorrect user interaction with the built-in tools.   

Due to the complexity of the IE11 changes of the selection object, with which the RadEditor control interacts to preserve the correct range the only possible resolution is adding a meta tag in the head element of the page to force the IE10 compatibility mode of the browser:

<meta http-equiv="X-UA-Compatible" content="IE=10">

The area shapes in Image Map Editor dialog couldn't be moved or resized in Internet Explorer 11.

Add a property for setting the default mode of RadEditor (Design, HTML, Previw). Currently this could be obtained using the approach in the following help article:

http://www.telerik.com/help/aspnet-ajax/editor-set-mode.html 

Linking an image inserted through the ImageManager via the LinkManager does not place the creating link on the right place - the <a> tag is inserted eithr inside the <img> one or beside it. The issue could be reproduced in IE11.

You can see the issue reproduced in the attached video.

Steps to reproduce:
1. Open http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx in IE11
2. Type some text in the Editor
3. Open the IamgeManager and insert an image
4. Select the inserted image and open the Link Manager

Expected result: the image tag is wrapped inside an <a> tag
Actual result: The <a> tag is inserted inside the <img> one

The layout of the editor's dialogs break when CSS for Window's lightweight mode are appended. This causes unavailability for the developers to use the  lightweight  feature of the Window

Due to this bug users cannot create HTML5 compliant pages with the RadEditor control.

To workaround the problem you can incorporate the JS method provided in this example:

<telerik:RadEditor runat="server" ID="RadEditor1">
    <Content>
        <nav>
            <ul><li>list item1
                </li></ul>
        </nav>
    </Content>
</telerik:RadEditor>

<script type="text/javascript">
    Telerik.Web.UI.Editor.Utils.isBlockElement = function (element) {
        return this.checkForElement(element, /^(?:body|p|div|h[1-6]|form|fieldset|table|thead|tbody|tr|th|td|ul|ol|li|dl|blockquote|address|hr|nav)$/i);
    };
</script>

This bug causes incorrect user behavior. Lists cannot be disconnected with Enter, in some cases user cannot add multiple empty paragraphs. 

To workaround this issue you can incorporate the JavaScript code provided in this example markup:

<telerik:RadEditor runat="server" ID="RadEditor1" NewLineMode="P">
</telerik:RadEditor>

<script type="text/javascript">
	var setCursorFn = Telerik.Web.UI.Editor.Utils._setCursorInNode;
	Telerik.Web.UI.Editor.Utils._setCursorInNode = function (cursorElement, container, editor) {
		setCursorFn.call(this, cursorElement, container, editor);
		if ($telerik.isChrome) {
			var selection = editor.getSelection();
			var range = selection.getRange();
			if (!range.collapsed) {
				range.collapse();
				selection.selectRange(range);
			}
		}
	}
</script> 

A workaround is to set the table element's height as well:

<telerik:RadEditor runat="server" ID="RadEditor1" Height="400">
</telerik:RadEditor>

<telerik:RadButton runat="server" ID="RadBtn1" AutoPostBack="false" 
    Text="Change Size" OnClientClicked="changeEditorSize"></telerik:RadButton>  

<script type="text/javascript">
    function changeEditorSize(sender, args) {
        var editor = $find("<%= RadEditor1.ClientID %>");
        var width = editor.get_element().style.width;
        editor.setSize(width, "200px");
        //this line is the workaround
        editor.get_mainTable().style.height = "200px";
    }
</script>