Time limit with two response options

I have a flicker paradigm set up (sequence of pictures that flash on the screen for 240 ms each). I am trying to it set up so that I have 2 possible response keys, one of which will continue on with the picture sequence and the other that will end the sequence. I've tried using the !meta function, but the pictures won't forward unless I hit one of the response keys. Is there another way to have the picture sequence continue on a set time until a participant hits the 2nd response key? I've looked into min-max functions, and I'd rather not use that. I'm running the drt file through medialab, unless that doesn't make a difference.

I have it worked out with the min-max function to have 2 response options and a set time for each trial. However, I have another problem. I have a masking image that is supposed to be up for 80ms between trial images (which are up for 240ms). If a response key is pressed during the mask towards the end of the time limit/during the inter-trial interval (or so I suspect from troubleshooting), rather than recording the response key, the response time is shown to be greater than 80ms with no record of the response key pressed.

I have rt:44, 50>1000, full under time, and then for min-max, I have 0-80! and 0-240! inputed.

Also, why when the key is held down, would the trial pause and not continue?