@DavidCarlisle, thank you for your help.
@JosephWright, we were discussing the use of boxes to avoid nesting of tikz pictures by enclosing inner picture inside a box (and I referenced one of your answers as an example). I also had to scale a custom-list bullet (drawn with pgf) to reflect currently selected font size (which wasn't simple for me to solve due to the boxing of the bullet picture: once you box, you can't change the contents, unless you know \resizebox exists [and I didn't]).