The Image Map Dialog is not rendered correctly because of a failure of the CSS reset. There is a margin-top attribute which is set with 15px value instead of 0.

Possible resolutions:
 1. Setting another Skin for the RadEditor control;
 2. Setting a custom stylization for the dialogs, which fixes the margin issue. For this approach you can test this example setup along with the provided DialogStyle.css file:

<telerik:RadEditor ID="RadEditor1" runat="server" 
	DialogsCssFile="~/Styles/DialogStyle.css">
</telerik:RadEditor>

More information about the DialogsCssFile property: http://www.telerik.com/help/aspnet-ajax/editor-dialogscssfile.html

Workaround:

<script>
    var $ = $telerik.$;
    Telerik.Web.UI.RadMenuItem.prototype._doAriaFocus = function () {
        var menu = this.get_menu();
        var menuId = menu.get_id() + "_active";

        $(this.get_element()).attr("id", menuId);
        $(menu._getMainElement()).attr("aria-activedescendant", menuId);
    }
</script>

The NewLine command behave inconsistently across browsers and causes different incorrect content generation in IE, Chrome and Safari.

 - In IE - New lines are added, but the cursor stays in the initial/first line. This issue also causes an performance problems when typing and pressing Enter with regular speed.

 - In Chrome - Pressing Enter causes mixed content of tracked and not-tracked text to appear without toggling the state of the Track Changes. Also, adds an empty INS tag in from of the new line.

 - In Safari - Adds an empty INS tag in from of the new line.


For the time being you can incorporate the JavaScript code from the following example:

<telerik:RadEditor runat="server" ID="RadEditor1" EnableTrackChanges="true">
	<Tools>
		<telerik:EditorToolGroup>
			<telerik:EditorTool name="AcceptTrackChange" text="Accept Track Change" />
			<telerik:EditorTool name="RejectTrackChange" text="Reject Track Change" />
			<telerik:EditorTool name="AcceptAllTrackChanges" text="Accept All Track Changes" />
			<telerik:EditorTool name="RejectAllTrackChanges" text="Reject All Track Changes" />
			<telerik:EditorTool name="EnableTrackChangesOverride" text="Enable Track Changes Override" />
		</telerik:EditorToolGroup>
	</Tools>
</telerik:RadEditor>

<script type="text/javascript">
	(function () {
		var $E = Telerik.Web.UI.Editor;
		var utils = $E.Utils;
		var isTypingKey = utils.isTypingKey;
		utils.isTypingKey = function (e) {
			return e.keyCode != 13 && isTypingKey(e);
		}

		var extractFrom = $E.InsertParagraphCommand.prototype.extractFrom;
		$E.InsertParagraphCommand.prototype.extractFrom = function (cursor, container) {
			var newElement = extractFrom.call(this, cursor, container);
			if (!this.get_editor().get_enableTrackChanges() || utils.isTextNode(cursor.nextSibling)) return newElement;
			$telerik.$(newElement).find("*").each(function (index, item) {
				if ($E.TrackChangesUtils.isTrackChangeElement(item)) {
					if (utils.isTag(item, "ins") || utils.isTag(item, "del")) {
						utils.removeNode(item);
						return;
					}
					$E.TrackChangesUtils.removeNodeTracking(item);
				}
			});
			return newElement;
		}
	}());
</script>

When the data is initially grouped and later grouping is collapsed, the group does not expand on click again.
The class rgExpand does not change to rgCollapse class.

It works with Telerik.Web.UI.dll version 2014.2.618.40 (release 1/14/2016?)

However, when we upgraded to 2016.2.504.40 (release 5/9/2016?), it is stuck in "Collapse" mode. Cannot expand again in when clicked on the arrow.

We need the exactly the same control that the guys over in Silverlight have:

http://www.telerik.com/products/silverlight/expressioneditor.aspx

I am in desperate need of this control in the ASP.Net platform.

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.

Per DISA security hardening requirements, unlisted file extensions should be filtered in URL requests as seen in the following DISA STIG: http://www.stigviewer.com/check/V-26046

To do this, the Telerik UI for ASP.NET AJAX must publish extensions that are used in the libraries.  Without the extensions being published, it is not possible to implement this hardening requirement since the application will not function properly due to the unknown extensions being blocked.  Please publish the library extensions being used so that the hardening setting to filter unlisted file extensions can be turned on.  If this cannot be done, please identify the reasoning so that a deviation from the hardening requirement can be approved by the security team.

Currently RadSplitter, RadWindow and RadDock (there might be other Telerik controls) apply default FontFamily and FontSize to their wrapper elements which is applied to the client's content as well.

Modifying client's content in any way is not correct behavior for layout and/or container control.

Currently, controls that have popups can have their z-index controlled as explained here: http://www.telerik.com/help/aspnet-ajax/controlling-absolute-positioning-with-zindex.html

RadComboBox has an explicit ZIndex property. Should all controls with popup elements have such a property?

It would be nice if all dropdown list controls (dropdownlist, radcombobox, etc) had a built-in "x" button somewhere which allowed the user to clear the selection of an item (ie set its selectedIndex to 0).

Clicking on the "x" would also fire the client-side and server-side (if applicable) SelectedIndexChanging and SelectedIndexChanged events.

It would be great to have a facebook-like auto expanding textbox with character counter.