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>