Is it possible to open a custom panel in the campaign UI? You can render a custom panel as part of a large intel screen, but what if I wanted to open a custom panel rendered on-top of an existing screen? Just like this in-game example:
It's not possible. Generally speaking, where the UI *is* moddable, it's moddable in very specific places/ways.
Is it possible to add to another tab to intel screen (e)?
It's not.
Is it possible to enable (in next version) rendering both small and large intel screens (currently if both hasSmall and hasLarge returns true, only large is rendered)?
Ahh, I don't think so - or, rather, it's probably *possible*, but it'd be a significant enough effort on my end and since it's not a path vanilla uses, there's a solid chance it wouldn't quite work right or I'd unintentionally break it at some later point etc.
It seems like you might be able to call the createSmallDescription method yourself, though, no? With a TooltipMakerAPI you've created to pass into that? Maybe I'm missing a piece that's not exposed that'd make this work...
And finally, should I keep on adding requests to API request thread, or just write a comprehensive list of UI requests in own thread (nothing new, just releasing what already is in-game in the form of API)?
The API requests thread is good! It may seem like I'm ignoring it, but that's not the case. I'll do my best to look through it and add what I'm able to add before the next release. Mostly it'll be the low-hanging fruit, in all likelihood - but then that sounds like exactly what you're talking about here.