Hopefully this is simple - I DataBind a bunch of labels and text controls in a Silverlight application (to DependencyProperties that I create in my class), but of course the text is empty at design time.
I'd still like to have an idea of how this will be laid out; is there a way to specify a design-time value, even though it's databound?
The feature you're looking for is Expression Blend Sample Data. Sample Data allows you to specify a Design Time data source that has some sample fields in it (names, addresses, numbers, images, hierarchies, etc).
Here's a good introduction article: http://silverzine.com/tutorials/how-to-create-sample-data-in-blend-3/
And here's a collection of links on Sample data: http://martinkruszynski.blogspot.com/2009/08/expression-blend-3-sample-data-data.html
The core of Sample Data is you use build a mock design time datasource in blend (shaped like your data types), define the type of sample data and the bindings get evaluated to give you a meaningful design time experience.