Context menu
§Application Level
§   Application.AddDefaultContextMenuExtension
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§Entity Level
§    Application. AddObjectContextMenuExtension –per RXClass
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You can add a context menu at the application level or you can have a context menu just for certain types of entities. The application level context menu displays when the user clicks on the drawing background. You add this context menu using  AddDefaultContextMenuExtension of the Application. In this example a context menu is being created. The class for a context menu  is the ContextMenuExtension and it has properties such as the Title. The ContextMenuExtension also has a collection of MenuItems. Here a menu item named M I is created and the constructor for it takes a string which will be the text the user sees on the menu item. When the user right clicks on the drawing background the context menu will display and there will be a new item on the menu with the text “circle Jig”. When they click on the menu, the menu items will display. In this case the menu item will have the text “Run Circle Jig”. When they click on the menu item, the function CallBackOnClick will be called. You can see that AddHander is used to control which function will be used. You can also create a context menu that will display when the user right clicks on a particular type of object. To create this type of context menu, you use AddObjectContextMenuExtension. Notice that one of the arguments for this method takes an RXClass. In this example the context menu will display when the user right clicks on any line in the drawing.  In the lab we will only be adding an application level context menu. However it would be easy to change it so it uses the entity example here instead.