CSS IDs and classes for panes are potentially rewritten in 3.6 update, breaking themes that rely on them

You are correct that the issue you linked introduced the problem. I realize now that the issue I created #2785917: Underscores in CSS IDs for panes are converted to hyphens after 3.6 update is similar to the one you reported here.

Thanks for filing this issue @karen11, and thanks to @bkosborne for citing your related ticket! Since this one came first I'm going to mark #2785917: Underscores in CSS IDs for panes are converted to hyphens after 3.6 update as a duplicate so as to focus all efforts here.

Actually @bkosborne, rather than closing your well-documented ticket myself, I'll suggest that you move your findings here if it's not too much trouble and close the other as a duplicate. :)

What's the reason for lowercase CSS classes? In my opinion there's no need to do so. That's why I created a patch that just removes the drupal_strtolower($class) function.

Marked my issue #2785917: Underscores in CSS IDs for panes are converted to hyphens after 3.6 update as a duplicate of this one, so we aren't splitting effort to fix the same root problem, as suggested.

@svenb, the reasoning for going to lowercase is detailed in this issue somewhere (I recall reading it yesterday): https://www.drupal.org/node/1441218 .... These changes were made so that you could insert tokens for the CSS class / ID, so there was an effort to make them more machine-name friendly. So a token for a taxonomy term "My Term" gets converted to "my-term"

I posted a patch for this same problem on #2785917: Underscores in CSS IDs for panes are converted to hyphens after 3.6 update. Re-posting it here! We're going to release Panopoly with this patch.

The issue here is that CSS classes are converted to lowercase and CSS IDs are run through drupal_html_id. Both are problems for existing panes. The patch addresses the issue with the CSS ID, but not classes.

Will need to examine the original patch that caused these problems to see all the areas that need to be reverted.

Here's a patch that removes usage of drupal_html_id and strtolower that was brought in from #1441218: Use keyword replacements for CSS settings. That issue did not properly consider the implication of existing CSS classes or IDs that would be transformed by the new code.

Assuming this is committed, another issue would probably need to be opened to come up with a better way to format the replaced tokens.

Oops, syntax error.

@bkosborne Thanks for that patch in #16! I've applied it to a local site running Drupal 7.44 (don't ask) and Panels 7.x-3.6; your patch fixes the broken theme for me. I'll test on other sites running Drupal 7.50 but can't imagine that will cause a difference!

Happy to report that the patch in #16 applies nicely and fixed the broken theme I encountered on two more Drupal 7.50 sites running Panels 7.x-3.6. Dare I say this is RTBC and ready to commit? :) Thanks again @bkosborne!

RTBC +1!

I can confirm that #16 patch works, for me at least…

Discussed this with @japerry at MWDS. He wants to have a working patch on #2787099: Add checkbox to normalize CSS IDs and classes before merging this one.

Makes sense, don't want to break sites that have been using the token feature either.

Okay we'll look at the normalization in the other patch. Fixed!