From Tracker Software PDF SDK
The event is fired before the Context Menu will be shown.
|Param1||PARAM_T||Contains the ID of the Popup Menu.|
|Handled||VARIANT_BOOL||Specifies whether the event was handled. Marking the event as handled will cause the event sender to look at the event`s result and act accordingly based on the event type.|
|Result||PARAM_T||Specifies the result that will be used by the event sender when the event is marked as Handled. In this case the Result is representing the Command ID from the Popup Menu that was chosen. If -1 is passed then the Context Menu won't be show and none of it's commands will be executed.|