The good news... I found the issue... and can now properly validate the data.
The not so good news - there are a few errors in the plugin template referenced in the doc - but nothing that can't be easily fixed - just took time to find.
The doc used is at:http://documentation.coppermine-gallery.net/en/dev_plugins.htm
and it's referenced subsections:http://documentation.coppermine-gallery.net/en/dev_plugin_api.htmhttp://documentation.coppermine-gallery.net/en/dev_plugin_steps.htm
references a template to download in Step 1 - cpg1.5.x_plugin_template_v1.0.zip
2 links provided to download - both point to V1.0.
showed no newer version available..
The provided 'admin.php' file has 3 issues I've found:
Line 31 - Common code for validating Checkbox and Radio Button input.
Properly validates Checkbox - including the case of 'unchecked' where the variable isn't provided in the POSTed variables, but it does not properly handle Radio Button input for values BETWEEN MIN and MAX. - These are rejected.
Line 53 - Common code for validating 'raw' input - freeform text (the issue that started this thread)
The tests try to compare a 'regex_ok' value from $san_value array. The key in the array is actually 'regex' - causing all input to FAIL validation.
Line 63 - Common code for validating 'array' input - from dropdown menus on form
These tests also reference the 'regex_ok' key - but in this case causes any input to BYPASS validation and be accepted...
A logic change to the Checkbox/radio button and variable change in either the array definition or tests against it is needed to correct.
(I changed the tests as I initially only found the 'raw' error - then went searching for other uses - and found the 'array' error. Changing the tests is a code change... Changing the array is a doc change... Code change seemed easier
I extracted the User Interface portion of my plugin and have attached a zip file that addresses these issues... Line numbers don't match the template values above - as I made other changes from the template - but a search on **GMC will bring you to my comments/changes.
The plugin can be installed and configured to validate the changes. It will take no other actions (functions called by filters other than install/deinstall only return provided data unchanged.)
Has examples of Checkbox, Radio, Dropdown, and Text variables to validate those cases.
I've provided an updated admin.php in separate attachment (admin.zip) that could be used to fix these issues...
(Since it is a starting template for a new plugin writer... didn't leave old code or comment changes as I normally would - to avoid confusion... Also didn't update version - as they should start their plugin with 1.0.)
The only doc change would be links to new template - if a different download filename is used.
(Referenced in Step 1 of http://documentation.coppermine-gallery.net/en/dev_plugin_steps.htm
Hope this helps the 'next person' trying to use the doc/samples to write a plugin.
Back to coding the real 'actions' I want done.
Thanks again to all.
(Didn't mark solved - as wanted to see if updates can be incorporated in provided template first.)