Multiple decals overlapping

After modelling a structure (usually a display), I have to put graphics on it.
I never use textures, because I always have to deal with printed items, so materials and texture never helps me; I always use decals, which are very useful when applying artworks.
The only problem is that when I have 2 overlapping decals, I never know where to place the second one to cover/not cover details on the first one. I always have to try a position, than move, than move…Is there any way to see in trasparence all the decals I already put on a surface/solid?

Thanks in advance!

nxt 5.0 works the way you’d like with decals in Rhino 5 SR13. The Rendered display mode also shows the decals and allows for editing the placement prior to rendering. There are move up and down buttons to reorder a list of multiple decals applied to an object too. Transparency can also be set in Properties>Decals and previewed in Rendered mode. Here’s a link to the latest v5 as well as nxt

http://www.rhino3d.com/download/rhino/5.0/sr
http://www.rhino3d.com/download/Flamingo/5.0/release

Thanks very much Brian!
Yesterday I downloaded SR13 (previously I had only SR12) and now everything works fine!