This method is invoked by a Generic Dialog if any of the inputs have changed
(CANCEL does not trigger it; OK and running the dialog from a macro only
trigger the first DialogListener added to a GenericDialog).
Perform curve fitting with the simplex method
doFit(fitType) just does the fit
doFit(fitType, true) pops up a dialog allowing control over simplex parameters
alpha is reflection coefficient (-1)
beta is contraction coefficient (0.5)
gamma is expansion coefficient (2)
Draws the specified ROI on this image using the stroke
width, stroke color and fill color defined by roi.setStrokeWidth,
roi.setStrokeColor() and roi.setFillColor().