G'day Discipulus,

I put the code and POD in a file, made a small change to the shebang line, and ran it without any options:

$ picwoodpecker.pl
Empty list searching [./*.jpg]!
bad event type or keysym "?" at /long/perlbrew/path/Tk/Derived.pm line
+ 469.
[download]

So my first suggestion was to allow the -source path to be selected after the GUI starts if none was specified on the command line (given the POD says this can be changed from the GUI).

Anyway, I tried again a couple of times using different paths with the -s option. Both gave an "ERROR creating a thumbnail ..." message as well as the "bad event type ..." message I noted above. I was able to independently open and view both images: they looked fine. I tried again with the -debug option you've supplied. Here's the entire output:

$ picwoodpecker.pl -s ~/local/doc/misc -debug
build_list received [/Users/ken/local/doc/misc]
DIR found: [/Users/ken/local/doc/misc] will be converted to [/Users/ke
+n/local/doc/misc/*.jpg]
Please wait while processing 1 files....
    adding /Users/ken/local/doc/misc/Mandel_zoom_00_mandelbrot_set.jpg
ERROR creating a thumbnail for file [/Users/ken/local/doc/misc/Mandel_
+zoom_00_mandelbrot_set.jpg].I will use an empty one.
bad event type or keysym "?" at /Users/ken/perl5/perlbrew/perls/perl-5
+.24.0t/lib/site_perl/5.24.0/darwin-thread-multi-2level/Tk/Derived.pm 
+line 469.
[download]

I also tried the widget demo. Both applications in the "Photos and Images" section worked without any issues.

I gave up testing at this point; however, I don't mind testing some more if you want to suggest other options, provide a URL to some test image(s), or make code changes.

In general, this does sound like a good idea. One further suggestion would be to allow other formats for the source images: adding Tk::PNG would be more useful for me personally (as an example, I searched my entire '~/local/doc/' tree for '*.jpg' files to test your GUI but only found 2; the same search for '*.png' files found 62).