Here’s an interesting gotcha if you are trying to cross-compile between Silverlight and WPF. The default content alignment of a ContentControl’s content in Silverlight is left/top while in WPF it’s stretch/stretch! The Silverlight ContentControl respects the VerticalContentAlignment/HorizontalContentAlignment properties (which default to left/top) while the WPF one does not. Check out the default templates of ContentControl in Silverlight and WPF for some other “cute” differences.