In my program, I'd like to use, say, the VEL procedure to overlay a velocity flow field on a contour plot in an iContour. Generally, how does one use any of the IDL procedures to overlay something on an iTool plot? It's easy to add other contours, surfaces, and such by just putting one iTool on top of another (e.g., call iSurface after calling iContour). But this seems to restrict us to adding only graphics explicitly supported by iTools. As far as I can tell, no iTool supports velocity flow fields, streamlines, or arrows. Anyone know a way to overlay velocity flow fields, streamlines, or arrows on an iTool plot? Regards. Greg