I actually recommend just using 'spindump' and reading the output in a text editor. If you just want to look through a callstack adding pretty much any UI just confuses things.

I am currently working on a native UI to visualize spindumps :(

Well try not to get the user lost in opening and closing all those call stack outline views, I'd rather just scroll in BBEdit ;)

It’s outline views, but I’ll see if I can keep an option to scroll through text too. (Personally, a major reason why I made this was I didn’t want to scroll through text like Activity Monitor does…)