I have a suggestion that I think would improve usability a great deal.
When selecting multiple signals to overplot in the same figure, it is very easy to select the name instead of just the "plus" sign when expanding the hierarchy and inadvertently cause the plot to disappear. Then all of the signals have to be selected again.
However, can you release an update for 2012b? In 2012b when evaluating the OpenFcn callback it tries to do close_system(gcs) which generates an error if the probe is at the top level of a model. If it is not at the top level of the model then it does not produce an error but it goes to the top-level of the model. You then have to use the back button to get back to your original spot.
Aditya -- no low pass filter is required, so no I'm not using one. Some form of delay would be required if the formulation I used created an algebraic loop in Simulink, but the way I modeled it no loop is created.