Graham, this is not a problem of R3GUI. If you want to access 'global' words of your script you need to provide the context to the module. Like:
REBOL []
if not value? 'to-text [ load-gui ]
v: module/mixin [
Version: 0.0.0
type: module
exports: [ test ]
][
test: func [] [
view [area]
]
] self
import v
test
AFAIK By default, the module imports only words defined in LIB context.
R3-GUI is not yet converted to module but once it is done we'll be able to specify something like needs: [r3gui] in the headers.