Let's say that you have RadPageView in ExplorerBar mode and the Content Size mode is set to AutoSizeToBestFit. Dock two buttons in the content area to top. Run the app and you will see that the bottom of the second button is cut in some themes. This is because these themes has a border set to the content area. The border is taken into consideration by the layout and the content is cut even throught there is space for it. This happens with Windows7, Office2010Black and other themes.