There is a black line that has appeared in my RadMenu.

The problem can be solved by adding a display: none in the following class:

.RadMenu .rmGroup:before, .RadMenu .rmMultiColumn:before, .RadMenu .rmScrollWrap>.rmHorizontal:before, .RadMenu .rmScrollWrap>.rmVertical:before

Load in IE this demo: http://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx

Enter in HTML mode - <p><a href="stm:b4f0c9ac-9a08-4c9f-8caf-39ccd4a83fc9" class="stm" contenteditable="false">Statement 111</a></p>

Switch to Design mode

Search for Statement with the Find and Replace dialog

The dialog won't be able to locate and highlight the link

The issue can be workarounded by calling preventDefault of the mousedown event when ComboBox item is clicked:
<telerik:RadScriptManager runat="server" />
<script>
	var onDocumentClick = Telerik.Web.UI.RadComboBox.prototype._onDocumentClick;
	Telerik.Web.UI.RadComboBox.prototype._onDocumentClick = function (e) {
		if (!e) e = event;

		var target = e.target || e.srcElement;

		while (target.nodeType !== 9) {
			if (!target.parentNode || target == this.get_element() || target == this.get_dropDownElement()) {
				e.preventDefault();
				return;
			}

			target = target.parentNode;
		}
		onDocumentClick.call(this, e);
	};
</script>

<telerik:RadComboBox ID="RadComboBox1" runat="server" RenderMode="Lightweight" OnClientBlur="OnClientBlur"
	CheckBoxes="true">
	<Items>
		<telerik:RadComboBoxItem Text="Item1" Value="1" />
		<telerik:RadComboBoxItem Text="Item2" Value="2" />
		<telerik:RadComboBoxItem Text="Item3" Value="3" />
		<telerik:RadComboBoxItem Text="Item4" Value="4" />
	</Items>
</telerik:RadComboBox>

<script>
	function OnClientBlur(sender, args) {
		console.log("Blur event");
	}
</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.

The dragging clue element is shown before the actual dragging of the element in the Grid is initiated (immediately after the item is clicked). The problem is reproducible in Chrome.

Comment: The problem is not reproducible in the following TreeView demo:
http://demos.telerik.com/aspnet-ajax/treeview/examples/functionality/draganddropnodes/defaultcs.aspx

Steps to reproduce:
1. Open http://demos.telerik.com/aspnet-ajax/grid/examples/columns-rows/rows/drag-and-drop/defaultcs.aspx
2. Click over an item (just mouse-down, without moving the mouse nor full click)
Result: The dragging clue is shown without actual moving of the mouse pointer

The issue is caused by a bug in the KB3057839 windows update. The bug has been reported to Microsoft and can be tracked at the following link:

https://connect.microsoft.com/VisualStudio/feedback/details/1475291

Currently the only workaround is to revert the KB3057839 update on the production server.

The long code lines in the QSF code viewer are very hard to read as the only way to get the horizontal scroll-bar is to reach the bottom of the page.

Under IE10 and 11 the CrossFade animation causes a random flickering.