When creating a UserControl in WPF, I find it convenient to give it some arbitrary Height and Width values so that I can view my changes in the Visual Studio designer. When
Here are a list of Design-Time Attributes in the Silverlight Designer. They are the same for the WPF designer.
It lists all of the d: values available in the Designer such as d:DesignHeight, d:DesignWidth, d:IsDesignTimeCreatable, d:CreateList and several others.