Not an expert, but if I remember right, you can open VSE and un-check the layers you do not want to show up. I just opened VSE2 and on one set the list on the left shows what is there. When I click off a couple of he layers, they did not show up. This might help.
Yeah, I'm talking about the layers that act like keyers when you have a 4 box open. I would like to be able to quickly turn those on and off and I don't see a way other than moving them offscreen which is weird.
Do this, take your 4 layer M/E and set it up as you would like. Then bring your cursor over to the left hand side of the M/E row on the interface. That little box will pop out, store your 4 layer M/E in the first slot. Don't move the position of anything, but now load up a 3 layer M/E, make sure that you have whatever layers you want selected and then save this M/E in the second slot. When you want to remove a layer, all you have to do is to go to the left hand side of the M/E row in the interface and click the proper M/E.
Understood, but if I want to use a 4 layer M/E and edit it to a 3 layer due to changes I need to crop or move layers out of frame if I don't need them. If I'm building a 4 box effect using keyers in an M/E and need to make a last minute change I can turn off a key, it's a small thing but it helps my workflow.