Millisecond Forums

I have 2 questions regarding presenting pictures with no response requirement: 

1. This it the code I have currently:

<trial Positive_Green_pos_1st>
/stimulustimes = [0=Forward_CS_Green_pos_1st; 4000=US_pos; 8000=Backward_CS_Green_pos_1st]
/timeout = 12000
/posttrialpause = 5000
</trial>

I want Forward_CS_Green to show for 4 seconds, then for it to disappear and for US_pos to show for 4 seconds, then for it to disappear and Backward_CS_green to appear for 4 seconds (picture offset coinciding with picture onset). When I run the trial above, the Forward_CS appears then disappears as the US_pos appears, but then the US_pos stays on the screen while the Backward_CS appears and they both disappear together. How do I stop the US_pos from remaining on the screen at the onset of the Backward_CS?

2. I would like to present 3 different inter-trial intervals - 5, 7, and 9s. Is there a way to do this?

I tried:

/posttrialpause = 5000; 7000; 9000 - but it only presented the 9s pause - is there a way to make Inquisit present these 3 different pauses randomly?

Thanks,
Luke