GemMan? (and by association, gemwin) disables alpha testing, alpha blending, culling, and lighting. Lighting defaults to two sided, with GL_COLOR_MATERIAL enabled. The viewport is set to:
float xDivy = (float)m_width / (float)m_height; glMatrixMode(GL_PROJECTION); glLoadIdentity(); glFrustum(-xDivy, xDivy, -1.0, 1.0, 1.0, 20.0); gluLookAt(0.0, 0.0, 4.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); glMatrixMode(GL_MODELVIEW); glViewport(0, 0, m_width, m_height);
which gives a range of about -4 to 4 in X and Y at the origin. This is a small range, but changing it now would break a lot of patches.
The specific functions to look at are: