@euphoria:
The Option you are talking about lets you decide in which way a sound behaves after you triggered it. As the symbols indicate, you can have a linear decay (or "fade out") or you can have no decay (which means, the sound will stay at it´s full volume until the "length" time is elapsed [or the sequencer note is over]). The second one is often useful for electronic sounds which you want to cut up hard at the end (like titancow said). If you want to use this option and want to have the notes in sequencer, you have to make the notes longer after creating them. But this is absolutely no cost, i think, because you can just mark ALL notes and make them longer by just dragging the end of ONE of the marked notes. So, it´s CTRL+A and 1 click. No cost. ;-)