src/Pure/PIDE/editor.scala

--- a/src/Pure/PIDE/editor.scala	Tue Dec 20 22:24:36 2022 +0000
+++ b/src/Pure/PIDE/editor.scala	Wed Dec 21 11:30:24 2022 +0100
@@ -27,7 +27,10 @@
     val changed =
       document_editor.change_result { st =>
         val st1 = f(st)
-        (st.required != st1.required, st1)
+        val changed =
+          st.active_document_theories != st1.active_document_theories ||
+          st.required != st1.required
+        (changed, st1)
       }
     if (changed) document_state_changed()
   }