Hi Carlo, there are some related things like you can hide faces to make objects displayed as wireframe, and also you can set View > Display hidden lines to make hidden edges and curves displayed in as faint dashed lines so you can see and select them through objects.

But those are not quite exactly the same thing. I'm sorry but it's not likely that I will be able to add transparency in the near future mostly because it greatly impacts performance. Video cards don't really support transparency directly, you have to draw polygons in sorted order to get a transparency like effect and that would incur a significant performance hit.

- Michael