Using custom visibility conditions in SpawnHeader, how creative can/should we get with it? Should it only really be used with group conditionals? I saw haste gave the example of "custom [combat] show;hide" I think. I wonder if you could use things like "custom [bar:n] show;hide" and make different layouts that you can cycle through if you bind your keys anyway and changing the actionbar page normally does nothing to your UI.
I'm also curious when the arena1 unit "exists". I assume it doesn't exist till they're targetable and probably go "noexists" when stealth which would render "custom [@arena1, exists] show;hide" probably useless. I'll have to test that one. My "custom [group:party,nogroup:raid][@raid6,noexists,group:raid] show;hide" works pretty good for arenas anyway though.