Currently, this command switches from Design to HTML mode and vise versa when EditType="Inline".

In Normal editing mode this tool is disabled in the HTML mode and cannot be used, although it is useful and provides yet another layout option for the default look of the RadEditor.

You can test the additional layout option by running this example:

<telerik:RadEditor runat="server" ID="RadEditor1"
    EditModes="Design" OnClientModeChange="OnClientModeChange">
    <Tools>
        <telerik:EditorToolGroup>
            <telerik:EditorTool Name="Bold" />
            <telerik:EditorTool Name="ToggleEditMode" />
        </telerik:EditorToolGroup>
    </Tools>
</telerik:RadEditor>

<script type="text/javascript">
    function OnClientModeChange(sender, args) {
        setTimeout(function () {
            sender.get_toolAdapter().getToolByName("ToggleEditMode").set_enabled(true);
        },0)
    }
</script>

This tool can be redesigned to be available in the HTML mode in all cases not only when Inline editing mode is enabled.

Issue: The value of the href property of a link is changed while modifying the content of the link.

Resolution:

This is a IE's feature and can be prevented by executing "AutoUrlDetect" browser command

<telerik:RadEditor runat="server" ID="RadEditor1" OnClientLoad="OnClientLoad">
</telerik:RadEditor>
  
<script type="text/javascript">
    function OnClientLoad(editor, args) {
        editor.executeBrowserCommand("AutoUrlDetect", false, false);
    }
</script>

More about the matter is available in this thread-- http://stackoverflow.com/questions/3519665/disable-automatic-url-detection-for-elements-with-contenteditable-flag-in-ie

There some issues when both features are enabled:

    - Add comment to tracked change is impossible;
    - Context menu is broken.

A possible workaround is to set the import step after all other rules in the CssFile of the RadEditor. CssFile would look like:

.h1
{
    background-color: Aqua;
}
.div
{
    color: Green;
}
@import url(StyleSheet.css);

A JavaScript error is thrown when a hidden AccessibleRadEditor is loaded in IE 10. The error message is:

"SCRIPT5007: Unable to get property 'get_element' of undefined or null reference "

Code to reproduce the issue:

        <asp:Button ID="btn1" runat="server" Text="Show Editor" OnClientClick="showEditor(); return false" />
        <div id="div1" style="display: none">
            <telerik:AccessibleRadEditor ID="AccessibleRadEditor1" runat="server" ></telerik:AccessibleRadEditor>
        </div>
        <script>
            function showEditor() {
                $telerik.$("#div1").show();
            }
        </script>

The first div element in the content is stripped out, every time a submit occurs with opened HTML tab.

When a parent control is disabled by setting Enabled to false, all children controls should inherit the behavior and act as disabled. RadEditor does not follow this logic and stays enabled. 

Workaround:
<telerik:RadTabStrip ID="RadTabStrip1" runat="server" MultiPageID="RadMultiPage1">
	<Tabs>
		<telerik:RadTab Text="tab1" Selected="true"></telerik:RadTab>
		<telerik:RadTab Text="tab2"></telerik:RadTab>
	</Tabs>
</telerik:RadTabStrip>
<telerik:RadMultiPage ID="RadMultiPage1" runat="server">
	<telerik:RadPageView ID="RadPageView1" runat="server" Selected="true">RadPageView 1</telerik:RadPageView>
	<telerik:RadPageView ID="RadPageView2" runat="server">
		<telerik:RadEditor ID="RadEditor1" runat="server" EnableTrackChanges="true"
			TrackChangesSettings-CanAcceptTrackChanges="true" ToolsFile="ToolsTrackChanges.xml">
			<Content>
				<p>paragraph 1</p>
				<p>paragraph 2</p>
			</Content>
		</telerik:RadEditor>

	</telerik:RadPageView>
</telerik:RadMultiPage>

<script type="text/javascript">
	$telerik.$.extend(Telerik.Web.UI.RadEditor.prototype, {
		_initEvents: function() {
			var editor = this;
			if (editor.__original__initEvents) {
				editor.__original__initEvents();
			}
			editor.add_domChange(Function.createDelegate(editor, editor._domChangedHandler));
			editor.attachInternalHandler("keypress", Function.createDelegate(editor, editor._keyPressHandler));
			editor.attachInternalHandler("keydown", Function.createDelegate(editor, editor._keyDownHandlerEnableTrackChangesOverride));
			editor.attachInternalHandler("keydown", Function.createDelegate(editor, editor._keyDownHandler));
		}
	});
</script>

The resize handle of the Editor is not visible if only only edit mode is active (e.g. Design mode).

Steps to reproduce:
1. Run an Editor with the following configuration:

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

Result: The whole module row is not visible, including the resize handle.

Using the desktop MS Word, pasting is fine. Using the Online version, the HTML gets messed up with plenty of unneeded DOM attributes and additional elements.

It would be best if pasting provides a cleaner HTML as it is when pasting form the desktop MS Word.

For example, checkboxes with plain text as labels before them do not appear selected in RadEditor:

HTML:

    Checkbox: <input type="checkbox" />

As the selection changes when typing inside textbox, JavaScript errors are being thrown. 

If the content contains html, head and body tags (Full HTML editing), and switching to Design mode causes a slightly slower rendering.

If the same HTML is used directly in the, the design mode renders as expected.

Web page hangs with long running script error when the Foreground color of table content is cleared in IE11.

Steps to reproduce:
1. In IE 11  Go to editor demo http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
2. Click HTML view and delete everything
3. Copy this into editor
    <html>
        <head>
            <title></title>
        </head>
        <body>
            <table>
                <tbody>
                    <tr>
                        <td style="color: #000000;">Lorem ipsum</td>
                    </tr>
                </tbody>
            </table>
        </body>
    </html>
4. Go to design mode highlight some text and click on the "Foreground color" button, select the clear choice (upper left)
5. Web page hangs with long running script error.  (It has something to do with that style on the TD)

End-users cannot clear class or apply class of block elements (i.e., <p>, <div>, <h1>, etc.,) when a class name already exists. 

In Firefox, 38.0.1, some text inputs cannot be typed into. They can be focused and the cursor appears to be in the input, but you cannot type.

If you try to re-format a paragraph with a link inside to a heading, the final result will be multiple headings split by the link.

The Rad Editor control removes unformatted spaces between differently-formatted words when the user presses Enter key for the first time in IE

Steps to reproduce:
    1. Go to http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx and clear all the pre-existing text.
    2. In the empty editing area, type two words separated by a space.
    3. Select the first word but not the space after it, and apply either italics, boldness, or underlining.
    4. Select the second word but not the space before it, and apply a different one of those formatting options.
    5. Position the cursor at the end of the line, and press Enter

Result: The space between the words will vanish. Firefox users will see underlining indicating that the browser considers the new, merged word to be misspelled.