When an Image or a Table elements are being inserted into the content of the editor, the undo command should revert the insertion.

When you copy a table from MS Excel and you paste it in the RadEditor under Chrome, an image that depicts the copied table will be inserted in the content area of the control along with the table.

You can use the following workaround to avoid inserting an image with the table:

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

        <script type="text/javascript">
            var getImages = Telerik.Web.UI.Editor.ClipboardImagesProvider.prototype.getImages;
            Telerik.Web.UI.Editor.ClipboardImagesProvider.prototype.getImages = function (event) {
                var images = getImages.call(this, event);
                debugger;
                if (event.clipboardData && images.length && event.clipboardData.getData("text/html")) {

                    return [];
                }

                return images;
            };
        </script>

Inserting a table is causing the user to switch to HTML mode and insert manually a br element, so that he could start typing in the next line.

Possible solution is attaching this Client-side method on the OnClientCommandExecuted event of the RadEditor control:

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


<script type="text/javascript">
    function OnClientCommandExecuted(editor, args) {
        var command = args.get_commandName();
        if (command = "InsertTable") {
            var selection = editor.getSelection();
            var range = selection.getRange();
            if (range.pasteHTML) {
                range.pasteHTML("<br />");
            }
            else {
                editor.pasteHtml("<br/>");
            }
        }
    }
</script>

The following workaround entirely changes the behavior by modifying the selection and selects the first TD

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

<script type="text/javascript">
    var identifierID = "RadEditor_AfterTable";

    function OnClientPasteHtml(editor, args) {
        var commandName = args.get_commandName();

        if (commandName === "InsertTable" || commandName === "TableWizard" ) {
            var currValue = args.get_value();
            currValue = currValue.replace(/<\/table>/gi, "</table><div id=" + identifierID + ">&#x200B;</div>");
            //currValue = currValue + "<div id=" + identifierID + ">&#x200B;</div>";
            
            args.set_value(currValue);
            setTimeout(function () {
                selectFirstTD(editor)
            }, 0);
        }
    }

    function selectFirstTD(editor) {
        var $ = $telerik.$;
        var contBody = editor.get_contentArea();
        var identifier = $(contBody).find("#" + identifierID);
        var table = identifier.prev();
        var elmToSelect = table.find("th")[0] || table.find("td")[0];

        if (elmToSelect.childNodes && !$telerik.isIE) {
            elmToSelect = elmToSelect.childNodes[0].nodeName === "#text" && elmToSelect.childNodes[0];
        }

        var hasNextElement = identifier.next()[0];
        
        while (hasNextElement && $(hasNextElement).is("style")) {
            hasNextElement = $(hasNextElement).next()[0];
        }
        
        editor.selectElement(elmToSelect);

        if (!hasNextElement) {
            table.after("<br/>");
        }

        identifier.remove();
    }
</script>

The main issue is the inconsistent behavior of the borders around the content area.

The initial problem is related with the JS error, because of which the editor's initialization is interrupted.  

You can workaround this by incorporating this piece of code:

<telerik:RadWindow ID="RadWindow1" runat="server" Width="805" Height="450" VisibleOnPageLoad="true">
	<ContentTemplate>
		<telerik:RadEditor runat="server" ID="RadEditor1" Height="200" Width="400" >
		</telerik:RadEditor>
	</ContentTemplate>
</telerik:RadWindow>

<script type="text/javascript">
	var oldCommand = Telerik.Web.UI.RadEditor.prototype.toggleEnhancedEdit;

	Telerik.Web.UI.RadEditor.prototype.toggleEnhancedEdit = function (newValue) {
		if ($telerik.isSafari && typeof (newValue) != "undefined" && false == this.disableContentAreaStylesheet(newValue)) {
			window.setTimeout(Function.createDelegate(this, function () {
				this.disableContentAreaStylesheet(newValue);
			}), 200);
		} else {
			oldCommand.call(this, newValue);

		}
	};
</script>

If a list is created and every bullet is with different stylization. Stripping all formatting is causing the content to be inserted into one bullet and the styles are not correctly stripped. 

When you add a symbol to the end of a line in IE, the cursor moves down to the next line.  This behavior does not exist in FF or Chrome, and it did not exist for IE in previous versions of the Editor.

Here is a video demonstrating the problem using the Telerik demo editor.

http://screencast.com/t/9S0TjfZzyFqj

When the Template Manager tool of RadEditor is enabled, the content of its dialog window is not loaded under IE.

When an edited image is saved in the Editor's ImageManager, the file is selected but the preview/properties areas on the right are not active. The user should click first on another image and then come back to the edited one, in order to be able to preview it or to change its properties.
Video, demonstrating the behavior: http://screencast.com/t/DAtzhgalHvA

1. Go to http:/demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx
2. Choose the bullet list command from the toolbar and type some text
3. Choose the FormatCodeBlock command and insert some text
4. Press SHIFT+ENTER to insert <br>

Actual: If you continue pressing enter, new lines will not be inserted.
Expected: New lines are inserted.

Under IE the get_text() retrieves only one word if there are many in the cells of a table.

This breaks the result of the RadEditorStatistics tool.

When multiple instances of RadEditor are placed inside hidden ASP Panel (visible='false') which is ajaxified with RadAjaxManager/RadAjaxPanel, and then the visibility of the ASP Panel is switched to true, the Statistics Module of the second, third.. Editors display 'undefined'. The issue is observed under Internet Explorer.

The workaround is to use:

-either ASP:UpdatePanel instead of the RadAjaxManager/RadAjaxPanel

-OR use the following JavaScript override:

            Telerik.Web.UI.Editor.Modules.RadEditorStatistics.prototype.doCount = function () {
            
                if (!this.get_visible()) return;

                var content = this.get_editor().get_text();

                var words = 0;
                var chars = 0;
                if (content) {
                    var punctRegX = /[!\.?;,:&_\-\–\{\}\[\]\(\)~#'"]/g;
                    content = content.replace(punctRegX, "");
                    var trimRegX = /(^\s+)|(\s+$)/g;
                    content = content.replace(trimRegX, "");
                    if (content) {
                        var splitRegX = /\s+/;
                        var array = content.split(splitRegX);

                        words = array.length;

                        var newLines = /(\r\n)+/g;
                        content = content.replace(newLines, "");
                        chars = content.length;
                    }
                }

                var elem = this.get_element();
                elem.innerHTML = "<span style='line-height:22px'>" + "Words:" + " " + words + "   " + "Characters:" + " " + chars + " </span>";
            }

In order to make the above function override working, it must be placed:

-Either below the RadScriptManager and load all the necessary resources through ScriptReferences of the RadScriptManager (disable the embedded resources of the RadEditors' instances too)

-OR create an additional instance of RadEditor in a hidden div, outside the AjaxPanel and place the function override below it.

The Insert Web Part tool in RadEditor for SP 2010 throws JavaScript error (reproducible in all browsers).

Steps to reproduce:
1. Open http://sharepoint.telerik.com/aspnet-ajax/web-parts/Pages/Content-Editor-Web-Part-using-RadEditor.aspx
2. Click over the content of the Editor, so the toolbar will be shown
3. Click over the Insert Web Part Tool

video - http://screencast.com/t/Df3aV6svUy

When navigating inside a table in the RadEditor, pressing the right arrow key of the keyboard moves the cursor only till the last table cell and the cursor does not exits the table. 

The error is Sys.InvalidOperationException: Sys.InvalidOperationException: Component 'RadEditor1_dialogOpener' was not found.

When not enabled RadEditor should merely show its content, when Enabled is toggled to true it should render toolbars and add its functionality.

A possible workaround is using the Visible property instead and a div with runat=server as a placeholder for the editor while it is not rendered (its Content property will still return the HTML in it). Thus, the innerHTML server property of the div can be used to set the HTML from RadEditor in it.

When I call OnParentNodeChanged on an Editor, while viewing the page using HTTPS, I get the following message in IE:
SEC7111: HTTPS security is compromised by (null) 

When using the Microsoft Edge browser with the Editor, you cannot add field values for some form elements. This seems to affect Radio buttons and checkboxes. It is possible that it affects other form elements as well. I also see this same problem when using your demo page https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx.

Edge does not offer the hasLayout capability of Internet Explorer, which selects the form element on click. In Edge you can select a form element as you could do it with a text: https://www.screencast.com/t/mo25Rm1kTSdB. The click selection is not currently supported.

I have a Telerik RadEditor (2017.3) control with custom/unembedded skin (created using the themebuilder on telerik), and when I enter a value for the DialogsCssFile attribute, the markup of the page changes, meaning that my custom skin is not applied to the editor anymore.

Why is this a problem? Well the css inside the dialog for Find/replace for example didn't display correct, and having done some research, I needed to do some @imports into a customDialog.css file and drop that into the DialogsCssFile attribute.

As soon as I do this, the generated markup in the page for RadEditor changes from

Radeditor RadEditor_MyCustomSkin reWrapper

to

Radeditor MyCustomSkin reWrapper

meaning that my radeditor Skin is not applied to the editor, If I remove the DialogCssFile then the editor skin loads correctly, but the dialogs look wrong. In the Page source, the Window is a div within the page, and not an iFrame

Code :

Page CSS files (in order)

<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/formdecorator.MyCustomSkin.css" />
<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/toolbar.MyCustomSkin.css" />
<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/window.MyCustomSkin.css" />
<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/combobox.MyCustomSkin.css" />
<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/dropdownlist.MyCustomSkin.css" />
<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/tabstrip.MyCustomSkin.css" />
<link type="text/css" rel="stylesheet" href="/assets/css/MyCustomSkin/editor.MyCustomSkin.css" />
Main Radeditor Class (to give idea of class names)

.RadEditor_MyCustomSkin { /* css styles - all generated automatically */ }
Control :

<telerik:RadEditor runat="server" ID="pageRadEdit" ToolbarMode="Default" EditModes="Design,Html"
DialogsCssFile="~/assets/css/MyCustomSkin/DialogHandler.MyCustomSkin.css"
ToolsFile="~/App_Data/Editor.xml" Width="980px" Height="800px"
EnableResize="false" OnClientLoad="resizeMe" NewLineMode="P"
OnClientSelectionChange="$page.setdirty"
ContentFilters="DefaultFilters,ConvertFontToSpan,IECleanAnchors,OptimizeSpans,MozEmStrong,FixEnclosingP"
EnableEmbeddedSkins="false">
        <SpellCheckSettings DictionaryLanguage="en-GB" AllowAddCustom="false" />
        <Languages>
            <telerik:SpellCheckerLanguage Code="en-GB" Title="English (UK)" />
        </Languages>
</telerik:RadEditor>
DialogHandler.MyCustomSkin.css

@import url('FormDecorator.MyCustomSkin.css');
/*@import url('Grid.MyCustomSkin.css');*/
@import url('Input.MyCustomSkin.css');
@import url('Splitter.MyCustomSkin.css');
@import url('TabStrip.MyCustomSkin.css');
@import url('ToolBar.MyCustomSkin.css');
/*@import url('Upload.MyCustomSkin.css');*/
@import url('Window.MyCustomSkin.css');
@import url('ComboBox.MyCustomSkin.css');
@import url('Button.MyCustomSkin.css');
/*@import url('Editor.MyCustomSkin.css');*/
Note : Editor css is still using wrong class even if the bottom import is uncommented

Web.Config settings

<add key="Telerik.Skin" value="MyCustomSkin" />
<add key="Telerik.ScriptManager.TelerikCdn" value="Disabled" />
<add key="Telerik.StyleSheetManager.TelerikCdn" value="Disabled" />
<add key="Telerik.Web.UI.RenderMode" value="lightweight" />
<add key="Telerik.Web.UI.EnableEmbeddedSkins" value="false" />
<add key="Telerik.EnableEmbeddedSkins" value="false" />

Based on customer feedback:

1) Toggle full screen
2) Finish AJAX spell checker
3) Then full screen icon is not selected even the editor is in full screen mode

When text in the Editor has Track Changes then :

• There should be Next/Previous menu icons to navigate through the Track Changes from one Change to another
• When a Tracked Change is Accepted/Rejected the cursor should move to the next Tracked Change