extjs combo won't stop loading 4.07

Question

I have 3 combo box's. When you click the first box the second box needs to update showing the relevant data. I select the first combo the second box updates perfectly. However if i try the same steps again the second box doesn't stop loading ( see image )

Here is the code from my view

{
    xtype: 'combobox',
    name: 'Clients',
    id: 'clients',
    displayField: 'Name',
    store: 'Clients',
    queryMode: 'local',
    mode: 'local',
    valueField: 'Id',
    fieldLabel: 'Clients'
},{
    xtype: 'combobox',
    name: 'Projects',
    id: 'projects',
    displayField: 'Name',
    editable: false, 
    store: 'Projects',
    queryMode: 'local',
    mode: 'local',
    valueField: 'Id',
    fieldLabel: 'Projects'
}

and from my controller

stores: ['Projects', 'Clients', 'Jobs'],

init: function () {
    this.control({
        '#clients': {
            change: this.onClientSelect
        },
        'processlist button[action=copy]': {
            click: this.onCopyPart
        },
        '#processColourContainer #processColourGrid': {
            edit: this.onPurchaseOrderColourUpdate
        }
    });
},

onLaunch: function () {             
    var clients = this.getClientsStore();
    clients.load();             
},
onClientSelect: function (selModel, selection) {

    var projects = this.getProjectsStore();
    projects.load({
        url: '/Projects/Read/?clientId=' + selection,
        scope: this
    });    
},

Answer 1

Known bug:

http://www.sencha.com/forum/showthread.php?153490-Combo-Box-Store-Loading

Adding this should sort it out:

store.on('load', function (store, records, successful, options) {
    if (successful && Ext.typeOf(combo.getPicker().loadMask) !== "boolean") {
        combo.getPicker().loadMask.hide();
    }
});