Execute synchronously MessageBox show function in ExtJs-5

I want to execute a Ext.Msg.show() function synchronously in ExtJs-5

onButtonClick : function() {
1. some code...
2. Ext.Msg.show({
            title : 'Confirm Please',
            msg : 'Please be informed that record will only save when click ok.',
            buttons : Ext.Msg.OKCANCEL,
            icon : Ext.Msg.QUESTION,
            fn : function(btn) {
                    if ('cancel' === btn) {
                        return;
                    }
                }
            });

3. other message box ...
4. other code ...
}

The above function execute synchronously each step 1, 2, 3 & 4 but doesn’t wait for user interaction on step 2. It directly move to step 3 and after that to step 4. But I want to execute step 3 only when user click on ok else terminate other below steps.

Can anybody check and let me know the possible code that I need to add to make it possible? Thanks