[from Shira Zimerman]
In order to keep the stimuli appear on the screen for their whole duration, regardless the participant's response, you should set min-max values in the style file (search for "MinMax" in the help index). If you want to change style for different stimuli written on the same line in your file you can use
write the new stile number in parenthesis: <style number> in the "stim" column (search for "styles" in the help index). In order to view multiple response answers you should use the "log" data file--in there you can find the RT for each one of the stimuli written you your line (search for "Multiple response times" in the help index).
Good luck!
Shira