lib/Ext/dataview/List.js
function(me, index, target, record, e) {
        if (!(this.getPreventSelectionOnDisclose() && Ext.fly(e.target).hasCls(this.getBaseCls() + '-disclosure'))) {
            this.callParent(arguments);
        }
    }
function(me, index, target, record, e) {
        if (!(this.getPreventSelectionOnDisclose() && Ext.fly(e.target).hasCls(this.getBaseCls() + '-disclosure'))) {
            this.callParent(arguments);
        }
    }
apply to the selection model to maintain visual UI cues