Triggers for interactive television display are incorporated into a video stream in coordination with graphics associated with the triggers. Graphic sources such as channels (16,18) of a character generator (21) supply graphics associated with the triggers to graphic signal inputs (26,28) of a switch. When a channel supplies a graphic, a message denoting the associated trigger and associating the trigger with the channel is forwarded to a gateway computer (60). The gateway computer monitors connections between graphic signal inputs (26,28) and the video output (32) of the switch, and forwards triggers associated with a particular channel to an inserter (40) only if such channel is connected to output (32).