Registers a pop-up menu with a particular id for extension.
Within the workbench one plug-in may extend the pop-up menus for a view
or editor within another plug-in. In order to be eligible for extension,
the menu must be registered by calling registerContextMenu
.
Once this has been done the workbench will automatically insert any
action extensions which exist.
A unique menu id must be provided for each registered menu. This id
should be published in the Javadoc for the page.
Any pop-up menu which is registered with the workbench should also define
a GroupMarker
in the registered menu with id
IWorkbenchActionConstants.MB_ADDITIONS
. Other plug-ins
will use this group as a reference point for insertion. The marker should
be defined at an appropriate location within the menu for insertion.