Does terraform support themes?

Yes. As of version 0.3.1 terraform properly supports Gtk themes. If you have a gtk theme on your system, you can enable it for your user by doing the following:

cp /usr/whereever/THEMENAME/gtk/gtkrc $HOME/.gtkrc

If you get errors about being unable to open theme files, you should edit your .gtkrc and add a line like this

pixmap_path "/usr/whereever/THEMENAME/gtk"

at the *beginning* of this file. Terraform should now load the theme upon startup.