when in a group, and travelling to a node from a content type tab, content type should be in breadcrumb as well as node

When a user is within a group, they click on a content type (e.g. discussions), click a node... then when they've finished with that node they generally click to go back to the group, which sends them back to the group front page, when they may have wanted to continue moving through the group discussions.

It would be better if in the breadcrumb there was also a link for the content type if they're arriving at the node from a content type context within a group.

I figure this would have to be done by adding a query string to node links in the group_tab_[type] views (like a referring url)... but I'm not exactly sure how then to append such info to the node breadcrumb.