(a) when a Fit is in progress and taking a long time, it would be useful to see the latest Cost Function in the progress bar, or somewhere on the dialog it is embedded in. In addition, maybe the parameters in the dialog / fit function pane could update every iteration or the fit curve overlaid on the data could be updated. I would then have an idea whether to let it continue, or cancel and retry with better guesses of the parameters. The actual percentage progress / estimated time is a bit arbitrary since it assumes it will go to the maximum allowed iterations.
(b) The Muon ALC’s Fit (when fitting lineshapes) doesn’t display a progress bar at all. The whole of Mantid just goes to “Not responding” until the fit is complete. Admittedly a simple Lorentzian fit on a spectrum of 50 points probably runs too fast to see the difference but there are more advanced functions available. Meanwhile the Muon Analysis embedded fit does have Progress. Muon ALC ought to have a “Plot guess” button / function too.
I’ve created some issues for these things to be looked at: