There is a missing label in the Box tab (Width and Height options) in the StyleBuilder dialog.

You can dynamically change the label by following this example:

<telerik:RadEditor runat="server" ID="RadEditor1" OnClientCommandExecuted="OnClientCommandExecuted">
    <Tools>
        <telerik:EditorToolGroup>
            <telerik:EditorTool Name="StyleBuilder" />
        </telerik:EditorToolGroup>
    </Tools>
</telerik:RadEditor>

<script>
    function OnClientCommandExecuted(sender, args) {
        var command = args.get_commandName();

        if (command === "StyleBuilder") {
            var dialog = sender.get_dialogOpener()._dialogContainers[command];

            dialog.add_pageLoad(fixSectionName);
        }
    }

    function fixSectionName(sender, args) {
        var dialogWin = sender.get_contentFrame().contentWindow;
        var label = dialogWin.$telerik.$(".reStyleBuilderBoxSize").find("legend");
        label.html("Dimensions");
    }
</script>

The editor does not go to edit mode. The problem occurs also when Auto mode is used. This prevents the developers to rely on the AutoResizeHeight functionality when a mix of all rendering modes is required. 

Possible workaround is to use the RadDeviceDetectionFramework - http://docs.telerik.com/devtools/aspnet-ajax/controls/raddevicedetectionframework - and programmatically disable the AutoResizeHeight in mobile devices:

ASP.NET
<telerik:RadEditor ID="RadEditor1" runat="server" RenderMode="Auto"
    AutoResizeHeight="true">
    <Content>
        <p>editor</p>
    </Content>
</telerik:RadEditor>

C#
using Telerik.Web.Device.Detection;

public partial class Default : System.Web.UI.Page
{
    private void Page_Load()
    {
        if (Detector.GetScreenSize(Request.UserAgent) < DeviceScreenSize.Medium) {
            RadEditor1.AutoResizeHeight = false;
        }
    }
}

For the time being you can safely use the same scenario with ContentAreaMode set to Div.

Currently, opening the CustomColorPallete popup always selects the #808080 color.

To have this behavior use the custom code solution below:

<telerik:RadColorPicker runat="server" ID="RCP" EnableCustomColor="true" OnClientLoad="OnClientLoad" />

<script>
    function OnClientLoad(sender, args) {
        $telerik.$(sender._customColorButton).click(refreshPalette(sender));
    }

    function refreshPalette(sender) {
        return function (evt) {
            var colorPicker = sender;
            var selectedColor = colorPicker.get_selectedColor() || "#808080";
            colorPicker._updateHslPaletteElementsUI(colorPicker._getRgbFromHex(selectedColor), null, true);
        };
    }
</script>

When selecting a table element in the content area via the Dom inspector, Delete Table does not remove the table. 

You can use the RemoveElement from DOM inspector as a temporary workaround.

We're using Telerik.ReportViewer.WebForms.ReportViewer for exporting to another files format but only exported to excel file I got error message below.

please help to advise for this error.

Server Error in '/' Application.
Attempting to get range {22,19}{10,3},Merged=False,Parent=printPackingList2[0], that intersects with an already merged range.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.InvalidOperationException: Attempting to get range {22,19}{10,3},Merged=False,Parent=printPackingList2[0], that intersects with an already merged range.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.
Stack Trace: 

 [InvalidOperationException: Attempting to get range {22,19}{10,3},Merged=False,Parent=printPackingList2[0], that intersects with an already merged range.]
   Telerik.Reporting.Excel97.Worksheet.GetRange(Int32 col, Int32 row, Int32 colSpan, Int32 rowSpan) +186
   Telerik.Reporting.ExcelRendering.Excel97.Worksheet.Telerik.Reporting.ExcelRendering.IWorksheet.GetRange(Int32 col, Int32 row, Int32 colSpan, Int32 rowSpan) +73
   Telerik.Reporting.ExcelRendering.RenderingItem.GetRange(IWorksheet worksheet, TableLayoutInfo layoutInfo) +381
   Telerik.Reporting.ExcelRendering.RenderingItem.Render(IWorksheet worksheet, TableLayoutInfo layoutInfo) +78
   Telerik.Reporting.ExcelRendering.RenderingItemContainer.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +141
   Telerik.Reporting.ExcelRendering.Section.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +62
   Telerik.Reporting.ExcelRendering.RenderingItem.Render(IWorksheet worksheet, TableLayoutInfo layoutInfo) +638
   Telerik.Reporting.ExcelRendering.RenderingItemContainer.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +141
   Telerik.Reporting.ExcelRendering.Report.RenderInternal(IWorksheet worksheet, TableLayoutInfo layoutInfo) +786
   Telerik.Reporting.ExcelRendering.RenderingItem.Render(IWorksheet worksheet, TableLayoutInfo layoutInfo) +638
   Telerik.Reporting.ExcelRendering.Report.Render(IWorkbook workbook) +373
   Telerik.Reporting.ExcelRendering.Excel97.ExcelReport.Telerik.Reporting.Processing.IRenderingExtension.Render(Report report, Hashtable renderingContext, Hashtable deviceInfo, CreateStream createStreamCallback, EvaluateHeaderFooterExpressions evalHeaderFooterCallback) +184
   Telerik.Reporting.Processing.ReportProcessor.RenderCore(ExtensionInfo extensionInfo, IList`1 reports, Hashtable deviceInfo, IRenderingContext renderingContext, CreateStream createStreamCallback) +1386
   Telerik.Reporting.Processing.ReportProcessor.RenderCore(String format, IList`1 reports, Hashtable deviceInfo, IRenderingContext renderingContext, CreateStream createStreamCallback) +103
   Telerik.ReportViewer.WebForms.ReportExportOperation.RenderReport(String format, IList`1 processingReports, Hashtable deviceInfo, IRenderingContext renderingContext) +259
   Telerik.ReportViewer.WebForms.ReportRenderOperation.PerformOperationOverride() +340
   Telerik.ReportViewer.WebForms.HandlerOperation.PerformOperation(HttpContext context, ICacheManager cacheManager) +74
   Telerik.ReportViewer.WebForms.BasicHandler.ProcessRequest(HttpContext context) +276
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +341
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69

http://demos.telerik.com/aspnet-ajax/editor/mobile-examples/overview/default.aspx

Error: Uncaught TypeError: Cannot read property 'Polling' of undefined

For the time being you can manually set the localization string for the "Add Custom Color" and "Current Color" buttons: 
		<telerik:RadEditor ID="RadEditor1" runat="server" RenderMode="Mobile" Language="de-DE" LocalizationPath="~/App_GlobalResources"></telerik:RadEditor>
		<script>
			var initialize = Telerik.Web.UI.Editor.MobileColorPicker.prototype.initialize;
			var addCustomColorTextLocalized = "Add Custom Color Localized";
			var currentColorTextLocalized = "Current Color Localized";

			Telerik.Web.UI.Editor.MobileColorPicker.prototype.initialize = function () {
				var colorPicker = this;
				initialize.call(colorPicker);
				
				colorPicker._addCustomColorText = addCustomColorTextLocalized;
				colorPicker._currentColorText = currentColorTextLocalized;
			}
		</script>

Using the RadEditor with Auto or Mobile mode in a RadWindow is impossible because JS error are thrown when dialog is shown. 

For the time being, the most proper solution for this case is using the Lightweight mode for RadEditor.

In the meantime, use the following workaround:

<script type="text/javascript">
                var designMode = Telerik.Web.UI.EditModes.Design;
                var editorPrototype = Telerik.Web.UI.RadEditor.prototype;
                var keypress = editorPrototype._keyPressHandler;
                editorPrototype._keyPressHandler = function (ev) {
                    if (this.get_mode() == designMode) {
                        keypress.call(this, ev);
                    }
                }
                var keyDownOverride = editorPrototype._keyDownHandlerEnableTrackChangesOverride;
                editorPrototype._keyDownHandlerEnableTrackChangesOverride = function (ev) {
                    if (this.get_mode() == designMode) {
                        keyDownOverride.call(this, ev);
                    }
                }
                var keydown = editorPrototype._keyDownHandler;
                editorPrototype._keyDownHandler = function (ev) {
                    if (this.get_mode() == designMode) {
                        keydown.call(this, ev);
                    }
                }
            </script>

Using this method to programmatically select the content area does not work as expected in Edge browser.

Possible workaround is to use ContentAreaMode="Div". Or using editor.get_contentArea().focus() method instead of editor.setFocus() (This might not work for some legacy browsers).

When the form element is offset, RadAutoCompleteBox popup is not properly positioned unlike the Combo / Dropdown counterparts.

Since we append all popups in the FORM element, the issue is only exhibited if FORM is not top level element, but is instead nested. The most obvious case is when you have Bootstrap structured page: .container > .row > .column.offset-3 > *form* > radautocompletebox.