sunburnt: GtkDialog1-1.3 will add directly to list without duplicates - run "examples/fselect2list_test" to test.
The problem with this is that the version of gtkdialog you reference is a group remake of gtkdialog that will not work with a lot of Puppy gtk scripts and until all of this is worked out with the version you reference included in most Puppys by default, one would end up with an application that required a specific version.
I remember the rewrites of scripts to comply with the latest version of gtkdialog by thunor.
And correct me if I am wrong. Gtkdialog 1-1.3 you refer to is a work/rewrite in progress.
I consider GtkDialog1-1.3 finished. I just suggest a solution - could even be just for inspiration of how it was done. Btw. several standard puppy holds more than 1 version of gtkdialog - so that can be handled too.