The tabs get hidden when a top oriented SlidingPane is docked inside a horizontal SlidingZone. The issue is reproducible when the resize mode of the parent Splitter is != AdjacentPane. Steps to reproduce: 1. Run the following code: <div style="padding: 200px"> <telerik:RadSplitter runat="server" ID="RadSplitter2" Orientation="Horizontal" ResizeMode="Proportional"> <telerik:RadPane runat="Server" ID="radpane11" Height="20px" MaxWidth="980" Scrolling="None" BackColor="Green"> <telerik:RadSlidingZone ID="ListMetricsSlidingZone" runat="server" Height="25px" DockedPaneId="ListMetricsPane" SlideDirection="Top"> <telerik:RadSlidingPane ID="ListMetricsPane" Title="DEF" runat="server"> 1111 </telerik:RadSlidingPane> <telerik:RadSlidingPane ID="ListHistorySlidingPane1" Title="XYZ" Font-Size="X-Large" runat="server"> 222 </telerik:RadSlidingPane> </telerik:RadSlidingZone> </telerik:RadPane> <telerik:RadPane runat="Server" ID="radpane33" Scrolling="None"> </telerik:RadPane> </telerik:RadSplitter> </div> 2. Undock and dock a sliding pane. Expected: The tabs remains visible all the time (change the Splitters ResizeMode="AdjacentPane" for reference)