[Chimera-users] How do I

I am using Chimera alpha version 1 build 2467 2007/10/31 I liked how each volume map opened has a different color. That's a great idea!! But I have a problem, I am displaying 4 volume maps at the same time. The volume viewer window only shows 3 histograms, therefore to modify the threshold of the fourth I have to close one of the volumes. Is there a way to modify the fourth histogram in the volume viewer window without close another? I also found a different behavior if you close the upper, middle and bottom histogram. Thanks.