"You have the skeleton of a script; you know the steps you want
to implement. How do you turn those steps into a Python
program?
"Fortunately, GIMP gives you a way of searching for functions:
the Procedure Browser, available in GIMP 2.6's Help menu. In GIMP
2.4 and earlier it was in the Xtns menu in the Toolbox window. Type
a pattern into the search field at the top and GIMP will show you
all the matching functions in its Procedural DataBase, or PDB.
"The first step in the blobify procedure is "Alpha to
Selection". If you're comfortable with regular expressions, you can
search for patterns like alpha.*selection and selection.*alpha.
Otherwise, just try each word separately and choose the one with
the shortest list -- in this case, "alpha".
"There are 28 procedures with "alpha" in the name. That's a lot.
But look through the list for something that also has "selection"
in the name and you'll find only one:
gimp-selection-layer-alpha."