In my own project I've begun to subclass certain Ext components into a new namespace Ext.sec. For example I have subclassed Ext.tree.TreeNode to override the unsafe text parameter.

Code:
var h = Ext.util.Format.htmlEncode;

TreeNode: Ext.extend(Ext.tree.TreeNode, {
    constructor: function(config) {
        if (config.text) {
            config.text = h(config.text);
        }
        Ext.sec.TreeNode.superclass.constructor.call(this, config);
    },
    
    setText: function(text) {
        Ext.sec.TreeNode.superclass.setText.call(this, h(text));
    }
})
I don't really want to publish the code yet since I am overriding functions and parameters on an "as required" basis and haven't done a review of the ext api. However if there is sufficient interest in doing this then I'd be happy to share it and work with other people.