A television display device for use with a television display for displaying television services, an input for providing at least one command to the television display device and a broadcast stream containing a stream of key files including data representing respective key images, the television display device including a memory for storing a plurality of control images and for maintaining continuously in memory at least one of said key files, an event selector for selecting an event and associating the event with a selected one of the plurality of control images, an action selector for selecting an action and associating the action with the selected control image, a display section for detecting the event and, in response, producing display information for displaying for a predetermined period the selected control image on a portion of the television display superposed on the television service being viewed and a command section for initiating the action conditional on whether or not a control command is provided by the input unit within said predetermined period, wherein, the display section, when displaying the selected control image, simultaneously displays the key image of one of the data files currently stored superposed on the television service being viewed and the command section executes the content of the key file of the displayed respective key image conditional on a key command being provided by the input unit within the predetermined period.