I ran against some troubles with "sourcery" lately (today actually).
I wanted to install dillo the web browser, so I fired up sourcery to install fltk13 first, but it wouldn't compile.

I noticed that "slackbuilds.org" is providing "fltk13 1.3.2" whereas 'sourcery' refers to a snapshot release, consequently I tryed to update 'sourcery' but It failed again.

Can you have a look on fltk13 with 'sourcery' ?