0bfedf7480
There are two keys: tab.owner and gBrowser._lastRelatedTab. tab.owner can appear even if the tab is opened without relatedToCurrent=true, for example, about:addons. On the other hand, gBrowser._lastRelatedTab is updated only when relatedToCurrent=true. So it seems more better trigger to attach a new tab to the parent automatically. This should fix #1065 (https://github.com/5digits/dactyl/issues/140)