DPlot

I often need to offset data so that the baseline of the graph moves to zero or some other value. I suggest a feature "offset baseline to XX" which moves the graph baseline to a user-specified Y value.

Well... first you need to tell me how to define the baseline. If you mean the minimum Y value, you can do this now with Edit>Operate on Y and Y=Y-$YMIN to shift the minimum to 0, or Y=Y-$YMIN+<some other number> to shift the minimum to <some other number>.

DPlot's definition of the baseline used during Info>Find Baseline... works just fine in the cases I've used. What I'm looking for is a packaged routine that calculates the baseline like Info>Find Baseline... does and operates on Y, without having the user (me) run Info|Find Baseline... , write down the baseline, then use Edit>Operate on Y and then enter the operation required and the number I wrote down.

I could add an option to Info>Find Baseline to subtract that value (and add another), but you'd still need to specify the start and end X values between which the baseline is calculated. If in your case your start and end values will always be the entire record, then what you want is already there, sort of, with Edit>Operate on Y and Y=Y-$MEAN.