Change tabs with mousewheel in Firefox 57

ff57-tabs-mousewheel.js

// Change tabs with mousewheel
// Run into Browser Toolbox console

var onTabWheel = function(ev) {
  if (ev.deltaMode == 1 /* DOM_DELTA_LINE */) {
    var idx = gBrowser.tabContainer.getIndexOfItem(gBrowser.selectedTab);
    if (ev.deltaY > 0) {
      if (idx + 1 < gBrowser.tabs.length) {
        gBrowser.selectTabAtIndex(idx + 1);
      }
    } else if (ev.deltaY < 0) {
      if (idx > 0) {
        gBrowser.selectTabAtIndex(idx - 1);
      }
    }
  }
}

gBrowser.tabContainer.mTabstrip._scrollbox.addEventListener("wheel", onTabWheel);

@Keith94 The first revision of the gist doesn't use mTabstrip. It might work with your version.

@fm3 Not that I know of. :(

The lastest version doesn't works with Firefox 58, but the first version works well.

Vote here to integrate this feature natively.

For compatibility with Firefox 58, in my fork I changed mTabstrip._scrollbox to arrowScrollbox. They renamed it in 1415537