I think you and I would like to have the same thing.  I've asked for functionality like you describe before, but perhaps not clearly enough. It'd be nice to have a "send to" command in the plot window interface that works like the "send to" functions in Windows.  What i would think the plot wiindow "send to" command would do is take the currently displayed spectra and more or less pipe that to spectral math, except without all of spectral math's limitations (can't read to/from a spectrum, has to also return a spectrum as output,etc.).  You should be able to write code to do anything  you want with the spectra being piped.  Even the plot's metadata (plot ranges, linestyles, etc.) should be piped. This would be *very* handy to have for a lot of the stuff i do and my group does.  As it stands, the best we can do is write a routine that grabs a spectrum from under the cursor of an image in a display, which kinda sorta gets me where we want to be, but then that creates limitations also.  Particularly if we want to take a spectrum from an image and then a spectrum from a spectral library and then run the same routine on it.  If we could pipe a spectrum from a plot window to our routine, we could easily do both.  I really hope this gets added to ENVI. Jeff