When zoom is applied in IE browser and button coordinates are not an integer RadImageButton tries to convert them to an integer on the server on postback and fails.

Workaround:

			<telerik:RadImageButton runat="server" ID="rib1" Width="50" Height="50" OnClick="rib1_Click" Image-Url="~/images/myImage.png"></telerik:RadImageButton>
			<script>
				Telerik.Web.UI.Button.ImageCoordsFunctionality.prototype._calculateCoords = function (e) {
					var container = this._ui.element;
					var pos = $telerik.getLocation(container);
					var scroll = $telerik.getScrollOffset(container, true);

					return new Telerik.Web.UI.Point(parseInt(e.clientX + scroll.x - pos.x), parseInt(e.clientY - pos.y + scroll.y));
				}
			</script>

The text in the tabs' titles of the Sliding panes of the Splitter control are not properly rotated.

Can be reproduced here:
http://demos.telerik.com/aspnet-ajax/splitter/examples/overview/defaultcs.aspx

http://demos.telerik.com/aspnet-ajax/splitter/examples/sp_firstlook/defaultcs.aspx

There are several other suggestions along these lines, but in general, Telerik needs to make their data input controls more consistent in the implementation of a "Label" property. Without such consistencies, it makes including controls that have this property and those that don't together on the same page much more difficult. As of the writing of this, the DropDownList and DatePicker controls do not have a Label property. There is no apparent reason why this should be so.

All of the input controls should have this property.

Related requests:

http://feedback.telerik.com/Project/108/Feedback/Details/149658-add-built-in-label-to-control

http://feedback.telerik.com/Project/108/Feedback/Details/66117-add-label-property-to-ajax-raddatepicker

Related annoyed forum thread about the omission of this property in the DropdownList control:

http://www.telerik.com/forums/dropdownlist-label#TI3zWYeMFESXjPIY_bYjZg

When adding a link with a class name, the Unlink command cannot remove the formatting. 

Temporary solution is to clear anchor's classes programmatically via the ApplyClass command:

<telerik:RadEditor runat="server" ID="RadEditor1" OnClientCommandExecuting="OnClientCommandExecuting">
    <Content>
        <a href="http://www.telerik.com" class="my-class">link</a>
    </Content>
</telerik:RadEditor>

<script type="text/javascript">
    function OnClientCommandExecuting(sender, args) {
        var command = args.get_commandName && args.get_commandName();

        if (command === "Unlink") {
            var myArgs = new Telerik.Web.UI.EditorCommandEventArgs("ApplyClass", null, "");
            sender.fire("ApplyClass", myArgs);
        }
    }
</script>

Please create high contrast theme for people with disabilities.

The best colors are yellow and black and there should be two combinations: yellow on black and black on yellow.

Please look at attachements for very good example.