function Leadtools.Annotations.Automation.AnnAutomation.showContextMenu()
This method will display the context menu not associated with any object. The AnnAutomation will call this method when the user right-clicks the mouse cursor anywhere in the Container surface but not on any of the objects currently in the container. You can call this method to show this context menu manually (for example, as a result from clicking on a certain menu item in your application).
The automation framework does not contain any context menu object, instead, the OnShowContextMenu event is fired and it is up to the application to show the UI.
Call the CanShowObjectContextMenu property to determine if the AnnAutomation is currently in a state where the object context menu can be shown