juliet

what I'm not sure about is whether that's because it wasn't happening or because nobody was kicking up a fuss about it.

The latter. Fewer women around (so harder for those who were around to stand up against it), fewer men who were even remotely aware, more uncritical acceptance. The whole 'booth babe' culture & general sexism of that sort has absolutely been around for a long time; sexist imagery as part of presentations ditto.

“Hey, a girl, we don't see many of these round here”, asking for dates, etc could perhaps be put down to plain immaturity; one might hope that it would decline as people grow up or when the gender balance improves.

But part of the point is that the gender balance *won't* improve (or will do so only very slowly) while this sort of behaviour is going on -- it's not OK for people (especially male people) involved in open source to say "well, it'll get better as more women show up. Come on women, show up and make things better for yourselves!". *Everyone* (and, again, that includes the *male* part of 'everyone') needs to act to improve things *now*, by noticing when even this milder variety of intimidatory sexism happens & calling people on it.

The active hostility: well, this most often shows up when someone says "hey, the open source community has these problems with sexism". And my guess is that it is in part because people don't like being called on their bad behaviour; so they turn on those who are doing the calling.

And then there's the more general stuff about privilege & the ways in which people who *have* privilege defend that privilege, and are not interested in contributions from unprivileged groups unless they choose to disguise their group membership. We live in a culture where men have privilege (google for "invisible knapsack" for more information), and the hostility and defensiveness on this issue in the OS community is just a manifestation of the same stuff elsewhere.