The links in Preview mode should not be opened at all or at least opened automatically in a new window, so that user could preserve its content.

Possible resolution is to invoke the setTargetsForPreview method on the OnClientLoad event of the editor:

<telerik:RadEditor runat="server" ID="RadEditor1"
	 EditModes="Preview" OnClientLoad="OnClientLoad">
	<Content>
		<a href="http://www.telerik.com">Link</a>
	</Content>
</telerik:RadEditor>

<script type="text/javascript">
	function OnClientLoad(editor, args) {
		Telerik.Web.UI.Editor.Utils.setTargetsForPreview(editor);
	}
</script>

This behavior stops the user to be able o insert these elements without being tracked

The link manager provides approach to add anchors with unique ID and name. The name should be inserted dynamically in a collection shown in the "Existing Anchor" drop down. For some reason this dropdown is never populated without reloading the RadWindow.

Possible resolution is forcing the dialog to reload on each show:

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

<script type="text/javascript">
    function OnClientCommandExecuted(editor, args) {
        var command = args.get_commandName();

        if (command === "LinkManager") {
            var dialogOpener = editor.get_dialogOpener();
            var linkManager = dialogOpener._dialogContainers[command];
            linkManager.add_show(function () {
                linkManager.reload();
            });
        }
    }
</script>

This property will define the MaxJsonLenght size.

Short version:  needed for IE browsers and overlaying external plugins such as PDF

To overlay external content such as PDF in some browsers, we need just Z-index. In other, we need an iframe inside the overlay.

This issue causes some content added by user to be not included when Track Changes are accepted. This is because the text is inserted in the INS tag, which is determined as deleted text by the feature's logic.

When trying to load a light-weight skin from external assembly (other than Telerik.Web.UI.Skins), the path to the files is not resolved correctly, hence no resource is loaded.

a radmenu  with input-fields would be very usefull
this would work the same way like a configuration-menu

This problem causes link and other elements to be added in the top of the content and not to modify the actual selected element. 

This issue is happening due to the insertion of the /n character in the comment editable area. This character breaks the logic of some content filters and they are replacing the greater than and less than characters in the HTML mode. 

Possible workaround is to disable the ConvertCharactersToEntities filter:

C# example:
RadEditor1.DisableFilter(EditorFilters.ConvertCharactersToEntities);

VB example:
RadEditor1.DisableFilter(EditorFilters.ConvertCharactersToEntities)

This issue causes incorrect user experience. The users are forced to do multiple actions to replace a word while using the Track Changes feature.

The image constrain tool in the image properties dialog is loaded as disabled by default. Mostly users easily can enable it the whole time, but the better user experience is this tool to be enabled by default. This way the user will be able directly to manipulate the image size without breking the correct proportions. 

Due to accessibility matters this shortcut currently focuses the last tool in the toolbar.

It would be great if developers could be available to modify the default behavior and attach a special command that behaves more like the MS Word's Shift+Tab command. The following behavior is the one experienced in desktop rich text editors:

    1. In text - The command adds a simple TAB (e.g. four white spaces).
    2. In list - The selected list item is being outdented.
    3. In table - The cursor moves to the previous cell.

A customization that provides such behavior can be easily implemented using a custom command and the addShortCut method:

<telerik:RadEditor ID="RadEditor1" runat="server" OnClientLoad="OnClientLoad">
    <Content>
        Text<br/>
        <ol>
            <li>Item 1</li>
            <li>Item 2</li>
            <li>Item 3</li>
            <li>Item 4</li>
            <li>Item 5</li>
        </ol>
        <br/>
        <table>
            <tr>
                <td>Cell</td>
                <td>Cell</td>
            </tr>
            <tr>
                <td>Cell</td>
                <td>Cell</td>
            </tr>
        </table>    
    </Content>
</telerik:RadEditor>

<script type="text/javascript">
    function OnClientLoad(editor, args) {
        var shortcutManager = editor.get_shortCutManager();

        if (shortcutManager.findShortCutByName("InsertTabMozilla")) {
            shortcutManager.removeShortCut("InsertTabMozilla");
            editor.addShortCut("InsertTab", "TAB");
        }

        editor.addShortCut("ShiftTabCommand", "Shift+TAB");
        editor.addShortCut("Underline", "Cmd+U");
    }

    Telerik.Web.UI.Editor.CommandList["ShiftTabCommand"] = function (commandName, editor, args) {
        var selectedElement = editor.getSelectedElement();
        var nodeName = selectedElement.nodeName;
        if (nodeName === "LI") {
            editor.fire("Outdent");
        } else if (nodeName === "TD") {
            Telerik.Web.UI.Editor.Utils.MoveToPreviousCell(selectedElement, editor);
        } else {
            editor.fire("InsertTab");
        }
    };
</script>

It was bug in the Firefox, and now works as expected. Here is markup for testing:
<script runat="server">  
    protected void RadTextBox1_TextChanged(object sender, EventArgs e)
    {
        newText.Text = RadTextBox1.Text;
    }  
</script>
<asp:Label runat="server" ID="newText"></asp:Label>
<telerik:RadTextBox runat="server" ID="RadTextBox1" AutoPostBack="true" OnTextChanged="RadTextBox1_TextChanged"></telerik:RadTextBox>
<asp:Button Text="submit" runat="server" />