[curt.clifton]

I don't recall this feature ever opening a new window. It just switches from project or context mode with the selected item still selected. It still seems to do that for me in 1.8 sneaky peeks. (Though I don't use that feature often anymore, so perhaps it was just recently fixed.)

Double-clicking an items handle in context mode opens a new window showing the item in project mode. Might that be what you were thinking of?