You can clone with
We should determine when a window.open call is intended to create a "popup" window, and not insert the sidebar in this case. At a minimum, the absence of the "toolbar" feature should be used as a clue.
check for toolbar being visible in rev 627c4b4. According to http://mxr.mozilla.org/mozilla-central/source/browser/base/content/browser.js#1360 that is the canonical check, so seems reasonable for now.
Reopening; I still see sidebar in some advertising popups. The location bar was present but no navigation controls.
Do we have a solid repro for this?
moved to https://bugzilla.mozilla.org/show_bug.cgi?id=755139