[TeMPOraL]

> I found myself doing it more often when the IDE itself downloaded and linked the sources. (Lazy, I know).

Same here. It's about trivial inconveniences. I sometimes can be bothered to download and read through the codebase of a dependency, but most of the times I end up in third-party code happen when it's just a single jump-to-definition keypress away - the same keypress (M-.) which I use all the time for my code. That seamless browsing really blurs the difference.