lib/Ext/core/Ext-more.js
function() {
        var map = Ext.ComponentManager.all.map,
            leaks = [],
            parent;

        Ext.Object.each(map, function(id, component) {
            while ((parent = component.getParent()) && map.hasOwnProperty(parent.getId())) {
                component = parent;
            }

            if (leaks.indexOf(component) === -1) {
                leaks.push(component);
            }
        });

        console.log(leaks);
    }
function() {
        var map = Ext.ComponentManager.all.map,
            leaks = [],
            parent;

        Ext.Object.each(map, function(id, component) {
            while ((parent = component.getParent()) && map.hasOwnProperty(parent.getId())) {
                component = parent;
            }

            if (leaks.indexOf(component) === -1) {
                leaks.push(component);
            }
        });

        console.log(leaks);
    }
<debug> 
Useful snippet to show an exact, narrowed-down list of top-level Components that are not yet destroyed.
@private