The toolbar API still lacks the required features to allow multirow. According to bugzilla discussions they might add it somewhere in 2018 :( You can also find contradictory statements from different developers like "this should be handled by addons" vs. "addons should manipulate only the web content not the browser itself" etc. It's a mess so maybe if we users push enough they might understand. See https://bugzilla.mozilla.org/show_bug.cgi?id=1246706
From my point of view they should also provide mouse gestures because the WebExtensions work only after DOM is loaded and not having gestures on internal pages is a huge discomfort and user experience dissonance to put it mildly.
> "addons should manipulate only the web content not the browser itself"
WTF? Who in their right mind can think that the only reason people installed add-ons was to manipulate the web content? UI is the main differentiating factor between browsers, FF strength was the ability to customize UI for user liking.
From my point of view they should also provide mouse gestures because the WebExtensions work only after DOM is loaded and not having gestures on internal pages is a huge discomfort and user experience dissonance to put it mildly.