[tw5] dropdown to filter journal entries

Hi! I have several tiddlewiki’s that I would like to combine, since they are similar or have related subjects. I typically take notes as Journal entries. I have a typical Journal tiddler like this:


…and I present it in a main page as a collapsible list of notes:

<$details summary=“Notes” open=“yes” state="$:/state/myDetailsContentsNotesStateTiddler">

If I combine all of my notes/journal entries in one area, I would like to select the subject. If I tag each journal entry with a subject tag, is there a way to present a drop-down of subjects that can be used in the toc? Maybe by default all tiddlers tagged with Journal, but a dropdown that I can select one (or more) subjects so that the search is for Journal and the subject tag?

Or is there a more elegant way of keeping journals for 3 subjects so that I can look at a list of journal entries for just one subject, or several subjects, or all subjects without hard-coding everything? I could create 3 different journal tiddlers, each hardcoded to one subject, but then as I add subjects, it gets to be more and more hardcoded sections and I miss being able to see all journal entries by date, regardless of subject.