The reb-value.h and reb-series.h files are part of some dependencies that really should be gotten rid of, and I think the only usage R3-View has is here:

struct rebol_series* img = (struct rebol_series*)GOB_CONTENT(gob);
int w = IMG_WIDE(img);
int h = IMG_HIGH(img);

That seems to be the sole use of rebol_series, and rebol_value is nowhere to be found. If that's it, and if RL_Gob_Width and RL_Gob_Height cover it, then I'm getting rid of those files now.

(I'll let you do add the RL_Gob routines in case you can think of something more generic like RL_Gob_Property that you might want...)