I am trying to style layers in a GRASS monitor such that they are partially transparent. I'm guessing that there's a module for that (d.shadedmap seems close), but I haven't found it. I need a solution for partial transparency in both vector and raster layers (including rgb groups). It would be great if you could provide instructions for how to do this with the wxGUI AND the command line, but I'm finding that I can learn most of the command line methods from the wxGUI while using it.
From the wxGui documentation:
A right mouse click on a layer or left clicking the button to the right of the layer opens a dropdown menu with options to remove or rename the layer (g.remove, g.rename), change its display properties (d.rast and d.vect options such as color, symbol, etc.), show its metadata (r.info, v.info) or attributes, if applicable.
In this menu you'll find the option Change opacity level.