STR: 1. Open Firefox Hello menu. (If all you see is "Getting started", click that, & re-open the menu) 2. Click the Cog/Gear icon in the bottom-right. 3. Hit "esc" key, or alt-tab, or something else to make the Hello menu be dismissed. 4. Re-open the Hello menu. ACTUAL RESULTS: The cog/gear submenu is still open. EXPECTED RESULTS: The cog/gear submenu should be closed, when you re-open the Hello menu. (It feels bizarre that the submenu's openness persists, through the top-level menu being closed.) Overall, the submenu's closing behavior feels unintuitive to me -- after you've opened it, it appears to remain open indefinitely (including inside of a closed top-level menu, as noted above in STR/actual-results) -- it remains open *until* you mouseover it, and *then* it aggressively closes as soon as your cursor moves off of it.

(Here's a screencast showing the sub-menu persisting even through top-level-menu-closing, until you mouse-over it, and then it eagerly closing as soon as the cursor moves off of it.)

Version info: Nightly 37.0a1 (2014-12-02) Mozilla/5.0 (X11; Linux x86_64; rv:37.0) Gecko/20100101 Firefox/37.0 Ubuntu 14.10

This has been improved in recent versions. There's only one remaining issue as far as I know, which is the menu stays open when you close via clicking on the loop button and then reopen without focusing anywhere else. That's covered by bug 1084291, so duping this there.