(is this the correct forum to ask my question?)
Moodle version 3.4.4
Theme custom, based on boost (parent)
My Moodle server has a default theme, let's call it FOO.
My course has a special setting theme = BAR.
Calling a page of a plugin, e.g /blocks/myblock/show.php?courseid=999 does display theme FOO when I want BAR.
I haven't found any function in $PAGE or $OUTPUT to set the theme of the course. Setting the PAGE context to the course context does not help.
What do I miss?