RadSpreadSheet control that can open and visualize excel files. It should also support edit and common operations.

This causes incorrect behavior. The STYLE tags should be removed along with the get_text method.
The origin of this problem is the behavior of the get_text method of the RadEditor control.

The following workaround can be used as a workaround for this issue. The implemented resolution is related to another logged bug - http://feedback.telerik.com/Project/108/Feedback/Details/119856

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

<script type="text/javascript">
	Telerik.Web.UI.RadEditor.prototype.get_text = function () {
		var $T = Telerik.Web.UI,
			modeEnum = $T.EditModes,
			oContent = "";

		if (this.get_mode() != modeEnum.Html) {
			var oArea = this.get_contentArea();
			if (oArea) {
				oContent = oArea.innerHTML;
				oContent = oContent.replace(/<br>/ig, "\r\n");
				oContent = oContent.replace(/<\/p>/gi, "\r\n");
				oContent = oContent.replace(/&nbsp;/gi, "\s");
				if (this.get_newLineMode() === $T.EditorNewLineModes.Div) {
					oContent = oContent.replace(/<\/div>/gi, "\r\n");
				}

				oContent = oContent.replace(/\s*<div[^>]*style="display:none;"[^>]*>[^>]*>\s*/gi, "");
				oContent = oContent.replace(/\s*<style[^>]*>[^>]*>\s*/gi, " ");

				oContent = oContent.replace(/<\/?[^>]*>/ig, "");
				oContent = oContent.replace(/<!--(.|\s)*?-->/gi, "");
			}
		}
		else {
			oContent = this._getTextArea().value;
			oContent = oContent.replace(/\s*<style[^>]*>[^>]*>\s*/gi, " ");
			oContent = oContent.replace(/<\/?[^>]*>/ig, "");
		}
		return oContent;
	};
</script>

Due to this problem end-users cannot manipulate the newly added areas and use the dialog properly. 

A possible workaround is to force the IE10 compatibility mode of the browser by adding the following meta tag in the head element of the page.
<meta http-equiv="X-UA-Compatible" content="IE=10">

The selected image in SharePoint RadEditor's Image Manager dialog is not displayed when edited in the Image Editor in IE when the property ImageManagerViewMode of the editor is set to Grid.

Certain controls just add bloat to a page.  Like the RadListView is a GREAT control to use inplace of the asp Repeater, but I find I often don't use it (or limit it's use) because it brings down 99.9% useless client scripts.  Most of the time, especially in Sitefinity its a server-side render-only control.  Just used to show data...we don't need ANY client manipulation.

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.

The issue is due to failing recalculation logic of the iframe content area. 

To resolve the issue you can use a RadEditor control with ContentAreaMode="Div" to render the content area as a DIV element, instead iframe.  

If the iframe mode is needed, you can use the following workaround to fix the content cell and the iframe appearance. 

<telerik:RadEditor ID="RadEditor1" runat="server" height="50px" OnClientLoad="OnClientLoad">
	<Tools>
		<telerik:EditorToolGroup>
			<telerik:EditorTool Name="Bold" />
			<telerik:EditorTool Name="Italic" />
			<telerik:EditorTool Name="Underline" />
		</telerik:EditorToolGroup>
	</Tools>
</telerik:RadEditor>

<script type="text/javascript">
	function OnClientLoad(editor, args) {
		setTimeout(function () {
			var editorIframe = editor.get_contentAreaElement(),
				originalIframeHeight = editorIframe.offsetHeight,
				contentCell = editorIframe.parentNode,
				cellSize = contentCell.offsetHeight,
				isCellSmaller = (originalIframeHeight - cellSize) > 2;
		
			if (isCellSmaller) {
				contentCell.style.height = originalIframeHeight + "px";
			}
		}, 0);
	}
</script>

Such functionality would improve the user experience for UI interaction of the end-users with the RadEditor tools.

Such behavior can be achieved using the following customization with the RadEditor control:

<telerik:RadEditor ID="RadEditor1" runat="server" OnClientLoad="OnClientLoad">
</telerik:RadEditor>
<script>
    function OnClientLoad(editor, args) {
        editor.attachEventHandler("onkeyup", function (e) {
            if (e.keyCode == 27)
            {
                closeContextMenus(editor.get_toolAdapter()._contextMenus);
            }
        })
    }

    function closeContextMenus(contextMenus) {
        for (var menu in contextMenus) {
            contextMenus[menu].hide();
        }
    }
</script>

The problem is when not tracked content does not exist. User cannot set the cursor outside the tracked content.
Although, typing should split the tracked text and user should be able to type in not tracked text when the feature is disabled.

I think you may consider the following similar type of control(s) in future release.  I think the following is a good fit for use between a BI solution and standard reports.  It gives regular users some flexibilities to generate ad-hoc queries within an application.

http://demo.easyquerybuilder.com/asp-net-ajax/

In case where RadButton is set as DefaultButton to the form or a panel and should trigger validation it does not PostBack the page regardless if the page is valid or not

Button single click becomes disabled permanently if a validation error is detected. After satisfying the validator conditions the button doesn't get enabled and it is not possible to post back the page.

This issue happens only under IE11 with IE9 compatibility mode. Using real IE9 browser the area is rendered correctly.

You should be aware of this issue when testing cross browser functionality of the RadEditor. 

With the current implementation if the RenderMode is set to Auto in the web.config file it is later automatically changed to Leightweight instead of Mobile.