Changing Q-range limits in Invariant Perspective has no effect on extrapolations

[smk78]

In the Invariant tab of the Invariant Perspective you can change the Min and Max Q values. My working assumption is that this is so that you can exclude points at either end of the data prior to the extrapolations? However, if you try this you will find that the extrapolations always use the full range of the data (ie, if you had a dataset with 50 points and opted to extrapolate the low-Q end with 10 points it uses points 1 to 10. If you were to then set a Qmin to exclude the first 10 points you would expect that it would extrapolate on points 11 to 20. It doesn't, it still uses points 1 to 10. The same behaviour happens with the high-Q extrapolations). So, is this by design? If so, why are the Total Q Range boxes editable?

I notice these boxes are not editable in 4.x.

Also see #1608