The design-time environment provides a Help system that attempts to locate relevant Help topics to display when a user presses F1. The Help system maintains a set of current context keywords that are used to identify relevant topics if Help is requested. By default, keywords are associated with selected class objects and properties of objects in the design time environment. The default keyword for a component or property is its fully qualified class or property name. Specific keywords are also associated with certain modes, such as when multiple objects are selected. If a custom Help collection is integrated with the design-time environment by configuring it for an external help provider, a documentation provider can associate a topic for a specific component class or property with a keyword consisting of the item's fully qualified type or member name.

The System.ComponentModel.Design.IHelpService can be used to invoke the help service with a specified keyword using the IHelpService.ShowHelpFromKeyword(string) method, or to invoke a help topic from a specified URL using the IHelpService.ShowHelpFromUrl(string) method.

The System.ComponentModel.Design.IHelpService can also be used to add or remove Help keywords at design time. Selecting a component or property at design time sets a default context keyword consisting of the fully qualified type or member name of the selection, and removes the keywords for any previously selected and no longer selected components or properties.

Because the Help system does not automatically remove custom Help keywords, you must explicitly remove a custom keyword when it no longer applies. You can monitor the events defined by the System.ComponentModel.Design.ISelectionService interface to determine when a component selection changes. Based on those events, you can add a Help context attribute for a component when it is selected and then remove the Help context attribute when the selection no longer includes the component.

Namespace: System.ComponentModel.Design
Assembly: System (in System.dll)
Assembly Versions: 1.0.3300.0, 1.0.5000.0, 2.0.0.0, 4.0.0.0