When I install an icon on one workspace it is installed on all four workspaces. Is it possible to install different icons on different workspaces? I am using Ubuntu 12.04.
Not an expert answer, but to the best of my knowledge, every default icon setting appears to be global in scope. Unity Tweak Tool, Gnome Tweak Tool, Gconf editor, Ubuntu Tweak (not a distribution package), and any other method appear to have a single, unified theme and icon set. The workspace settings in gconf-editor were deprecated after Gnome 2.12, and even then, don't believe individual workspaces with unique icons were available.
It is a nice idea, but the code around that idea is not at present available to the best of my knowledge.