Hi Reiner
I'm at work so can't spend a lot of time being too specific but can follow up later if you have more q's. Bare in mind I'm doing this from memory so take it with a pinch of salt.
You need to differentiate between the Gas 6 "function" and the Active? "Menu"
This is a picture of the previous behaviour in 1.80:
https://picasaweb.google.com/lh/photo/D ... directlink
The user manipulated the O2+/- and the He+/- lines to configure gas 6 and then go
UP to the first line and select "enter" to start using gas 6 and exit the menu.
That behaviour hasn't changed.
Now the question is why are you using a gas that you didn't programmed in the very beginning? The answer may be that you forgot and there is no pannic and therefore no big deal. However, another possible answer is that you lost one or more gases.
The problem at this point in time is that your deco obligation is incorporating all of your active gases to get you out of the water. The computer will kick out of the deco calculations any gas you are supposed to use at a certain depth and you haven't used. However common sense will tell you that the sallow part of the deco will be extended as a result of this inefficient deactivation of the gasses. Wouldn't it be nice that if you just suffered the loss of one or two gases to have the ability to kick them out and have your deco recalculated based on the remaining ones then and there as opposed to doing it in parts as you ascend?
Even better, to be able activate plan B such as the exact gases that your buddy is carrying by pre programming his gases on your spare ones but not activate them unless they are needed?
Therefore, enter the "Active?" menu. If you use the "menu" button to highlight "Activate?" and then press "enter" a menu with gases 1 to 5/6 will appear. Some gases are blue and some are white. By pressing enter on any of them you will turn some ON (white) or OFF (Dark Blue).
Once you exit the menu the decompression obligation will be recalculated based on those gases active at the time.
You do not need to manipulate gas 6 to manipulate the Active? menu. If you are diving G1 Nx50% and G2 Air and all other off and you loose with your Nx (such as a stuck valve) you can switch back/stay on your G2 and then kick G1.
Therefore all deco obligations will be calculated solely based on G2.
You could activate the previously programmed but not active G3 100% O2 that is hanging at 6m just in case or you could use the gas 6 settings to enter the TC xx/yy that a kind diver has just donated you.
The sky is the limit.
I hope this helps.
D
PS. We really need an online manual/"drupal book" where we can contribute with documentation.