Problem/Motivation
From #2664830-150: Add search capability to help topics (ambermatz): It is jarring [i.e., a usability bug] to enter a help search query at admin/help in the Seven (or administrative theme), then have the search results show up in the default theme (e.g. Bartik), then click on a help topics result going back to Seven (admin theme). (This is when you have the experimental Help Topics module enabled.)
For the same reason, user and node searches should continue to display in the default theme, because you usually initiate a search from that theme, and if you click through to a content item or user profile in the search results, you will be in the default theme.
So, search page plugins need the ability to specify that their results should show in the admin theme, or not.
Proposed resolution
Add annotation to search page plugins to make them display in the admin theme or (if omitted, the default) the regular theme.
Remaining tasks
[Done] Make a patch, including an automated test.
[Done] Test manually.
[Done] Create a follow-up issue to use this new annotation for the Help Search plugin that is part of the experimental Help Topics module (patch has already been verified to work with this issue's patch)
#3087879: Use admin theme annotation for help topics search
User interface changes
Some search page plugins (namely the Help search provided by the experimental Help Topics module) will have display their results in the admin theme, while all others will continue to display in the regular theme.
API changes
Nothing changes for existing plugins, as the default is still to display in the default theme. Search page plugins that want their results to display in the admin theme can add the "use_admin_theme" annotation to the annotation header in the plugin class (a follow-up issue will make this one-line change to the Help Topics module).
Data model changes
None.
Release notes snippet
New feature added for Search Page plugins: They can add "use_admin_theme = TRUE" to their plugin annotation and their results will be displayed in the admin theme instead of the default theme. Existing plugins (without this annotation) will default to FALSE, so their results will be displayed in the default site theme.