fm3

/* To enable changing tabs by using the mouse wheel,
 * enter this code into the browser console (Ctrl+Shift+J) */

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

benoitryder

// 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);
      }