The border of the splitbar disappears on hover. The issue is reproducible in IE - http://screencast.com/t/QfaZIZirSZfB

If the title of a SlidingPane is more than 22px it gets truncated in vertically oriented Splitter. The issue is reproducible in IE11 and IE8 here:
http://demos.telerik.com/aspnet-ajax/splitter/examples/sp_firstlook/defaultcs.aspx

Hovering the tab of a SlidingPane will render the pane only the first time, after the second hovering only the title of the SlidingPane will be rendered. The issue is reproducible both in enabled and disabled ClickToOpen, in IE8.

Video: http://screencast.com/t/jFhmqoJR

When a Tab of a Vertically oriented Splitter have both title and icon, its height is not calculated properly (the height of the icon is not taken into account). The issue is reproducible in Chrome.

Screenshot: http://screencast.com/t/0aaMryaShXZe

The HTML5 related changes in the RadSplitter have specific selectors that influence the content inside.

 The title of the SlidingPane is truncated in IE8 - http://screencast.com/t/yiJCR8DRp

Workaround:

        .rspSlideContainer td.rspSlideTitleContainer div.rspSlideTitle
        {
            width: 100% !important;
        }

When a Sliding pane have to be resized over a RadPane, containing a heavy weight object (Silverlight, PDF, Flash, etc.) its size is not calculated properly.

The border size of the RadPanes is always inherited by their parent Splitter's BorderSize, ragardless of the value set to the Splitter's PanesBorderSize property.

When the content of a RadPane is set through its ContentURL property, the RadPane cannot be scrolled in order to how its full content in IPAD.

The issue could be reproduced here: http://demos.telerik.com/aspnet-ajax/splitter/examples/externalcontentloading/defaultcs.aspx

When a RadPanelBar (having have more than 1 level of nested items) is nested inside a SlidingPane, it cannot be scrolled after expanding in iOS.

The scroll position of the radPanes is not pesisted after a postback (even if the PersistScrollPosition property of the Pane is set to "true").

When RadSplitter is declared in a page with no Doctype the RadSlidingPane stops responding in IE and the layout looks broken when docking/undocking.