FYI: there is now a 'fully' functional setup available, including the Lazarus IDE built against YTK, and a set of step-by-step installation instructions from Fred vS: ?
https://forum.lazarus.freepascal.org/index.php/topic,73590.msg578481.html#msg578481

Fred (Fred vS), Frank (fifr) and myself have all built different applications that appear to work just fine. so far the only major thing i've noticed wrong with the IDE is that autocomplete (ie, type "label1." and the IDE offers a list of fields to go next) throws a non-fatal error. i'm guessing this is likely due to a component that is missing from YTK that needs to be brought over from the GTKs source.

cheers,
rob :-)