The Pari-GP functions Ploth & Plothsize are failing within SAGE
Both Ploth & Plothsize are returning the "high resolution graphics disabled" message. There are several references on the Pari-GP website to this error messages.
These functions work fine on my standalone windows version of Pari-GP
eg: ploth(X = 0,2*Pi,[sin(X),cos(X)],1) will draw a circle.
