I've been looking at the captchas in some of the existing site forms, and it seems like the forms themselves never actually validate the captcha. For example, captchas in the Reply form seem to be checked not by the form itself, but rather the binary macro for actually posting a reply. Is there a way to validate captcha input in a custom form?
(Presently, I used NAML to create a form similar to "Reply to author", allowing people to e-mail users by clicking a link in the custom profile pages. "Reply to author" used a captcha that I couldn't figure out how to mimic, though. It's not a major problem; I'm just curious if I'm missing something.)
We have moved the captcha validation to an independent command that you can use in your custom form. The command name is check_captcha and you can search for this string in the macro viewer to see the usages (currently in process_registration and handle_anonymous_submit). Please let me know if you have questions, comments or concerns.