What is the (DynamicProperties) item listed on a control’s property page in VS.NET
Clicking Advanced... under this DynamicProperties option in the control properties displays certain control properties that can be set through an XML app.config file that is added to your project. This file stores the dynamic property values and is automatically read during the initialization process on the form at design time. You can manually edit this file to change the properties and next when you run the application, controls will pick up the new values. This file is used strictly for design time initializations.