Hello,
while migrating from 5 to 7 I stumbled over a major bug: Using Ext.menu.Menu it's not possible to scroll at all in some browsers (e.g. Firefox). In chrome scrolling is partially working (wrong direction and not smooth at all).

https://fiddle.sencha.com/#fiddle/37fj

Code:
Ext.application({
    name: 'Fiddle',


    launch: function() {


        var scrollMenu = Ext.create('Ext.menu.Menu', {
            height: 300,
        });


        for (var i = 0; i < 50; ++i) {
            scrollMenu.add({
                text: 'Item ' + (i + 1)
            });
        };


        Ext.create('Ext.panel.Panel', {
            width: 500,
            height: 500,


            items: [{
                xtype: 'toolbar',
                width: '100%',
                height: 40,
                items: [{
                    text: 'Scrolling Menu',
                    menu: scrollMenu
                }]


            }],
            renderTo: Ext.getBody()
        });
    }
});
A workaround is to set the overflowHandler to null inside the layout of the menu and set scrollable to true (or to y: true). However, that leads to default scrollbars being applied to the menu which looks awful and doesn't really fit a proper menu, especially when there are more sub menus inside.

This worked in Ext5 and also in 6.0 as far as I tested it. Imho this is a cruicial thing and I would be glad if either a fix or a workaround could be provided.