[OPEN-144] Scrolling a sortable breaks

[meyerovb]

Load the below example on an iPhone and sort by dragging the icons
Works fine on load, but once you scroll down, any further sorting breaks

Ext.setup({onReady: function () {
var items = [];
for (var x = 0; x < 20; x++)
    items[x] = { html: 'item' + x,
        dockedItems: [{ dock: 'right', xtype: 'button', ui: 'mask', stretch: false, iconCls: 'settings'}]
    };
new Ext.List({ fullscreen: true, scroll: 'vertical', id: 'list', items: items });
new Ext.util.Sortable('list', { direction: 'vertical', constrain: true, itemSelector: '.x-panel', handleSelector: '.x-button' });
}});