So this I actually do see happening already.

From @Ejegg: This other ticket: T243012 is about showing the full list under the tree selector (rather than just the count of countries and regions) so that people can see at a glance what's selected, without scrolling through the whole tree selector.

From me: Gotcha!

In my initial investigation, it looks like we can't mimic the exact way it looks in the columns because as of now, the columns in Special:CentralNotice use region numerical codes and what's available in js for the selector tree is either the text name or a letter code.

Current thoughts:

• If we're going to display the regions the same way as the dashboard, I for some reason am blanking on how to group them all by country and then convert to a string. In one iteration I had the object but my brain wouldn't recreate how to pull it out into a string.
• I've wondered how the UX will be if the list is too long and played with some other formats, though as I write I'm thinking the first is probably best. (Other formats like, listing countries, then saying X number regions in another countries list.)

Actually since writing that I'm much closer on the first problem, just have to remember how to slice off the last two characters of a string.

https://gerrit.wikimedia.org/r/c/mediawiki/extensions/CentralNotice/+/576153

@Ejegg @AndyRussG this is the patch.

@spatton @Pcoombe @TSkaff

Check out the changes we have made for Geotargeting in the CN staging sever here:
https://cn-stage-2.wmflabs.org/w/index.php?title=Special:CentralNotice&subaction=noticeDetail&notice=test_campaign1
That link will take you directly to a test campaign where you can see the tree selector for countries (screenshot also below). Let us know what you think of this.

This looks good! The arrows to expand a country could be a bit more obvious though. I like the filter, and also how it tells you what is currently selected below.

Change 591123 had a related patch set uploaded (by AndyRussG; owner: AndyRussG):
[mediawiki/extensions/CentralNotice@master] Include region code with name in tree selector

https://gerrit.wikimedia.org/r/591123

Change 591123 merged by jenkins-bot:
[mediawiki/extensions/CentralNotice@master] Include country and region codes in tree selector

https://gerrit.wikimedia.org/r/591123