ExtJS RowExpander plugin overriding default getRowClass

ExtJS (3) is great for OO style interface design but has a couple of strange behaviors. For instance when adding the ExtJS RowExpander plugin to a grid, the plugin overrides the gridView’s getRowClass function. That’s not really what you want. For instance, I want to mark certain records in a grid red when they are overdue, and also use the RowExpander plugin. The plugin however throws away my own custom formatting.
Solution is to create a backup copy of the default getRowClass function and call both the plugin function and the original, concatenating the results together with a space

getRowClass: function(record, rowIndex, p, ds) {
    p.cols = p.cols - 1;
    var content = this.bodyContent[record.id];
    if (!content && !this.lazyRender) {
        content = this.getBodyContent(record, rowIndex);
    }
    if (content) {
        p.body = content;
    }
    return this.state[record.id] ? 'x-grid3-row-expanded' : 'x-grid3-row-collapsed';
},

/*	If grid already has a getRowClass, don't override it
 *	get the original class and combine it with our class
 */
// @private
combineGetRowClass: function(record, rowIndex, p, ds) {
    var cls = this.originalGetRowClass(record, rowIndex, p, ds) + '"" + this.getRowClass(record, rowIndex, p, ds);
    return cls;
},

init: function(grid) {
    this.grid = grid;

    var view = grid.getView();

    /* create a backup copy of the original, we want to apply both the standard and our custom functions */
    if (view.getRowClass) {
        this.originalGetRowClass = this.clone(view.getRowClass);
        view.getRowClass = this.combineGetRowClass.createDelegate(this);
    } else {
        view.getRowClass = this.getRowClass.createDelegate(this);
    }

    view.enableRowBody = true;

    grid.on('render', this.onRender, this);
    grid.on('destroy', this.onDestroy, this);
},

// @private
clone: function(obj) {
    if (obj == null || typeof(obj) != 'object') return obj;

    var temp = new obj.constructor();
    for (var key in obj)
    temp[key] = clone(obj[key]);

    return temp;
}