I'm new to IDL, and try to understand the way objects work.I have downloaded the Motley library and try to change the design of MGH_EXAMPLE_2PLOTS Any one know how graphs in that library works? My first problem is, once the two plots are created, how do I later update the graphs with new data? It seems that I have no access to the x-data and y-data, but it is probably because I don't understand the concept of 'model' and 'atom' used by the graph object thanks, Stefan