Add Windows Explorer-like typing search to TUniListBox

[Sherzod]

Implements a familiar UX where typing letters moves the selection to the first matching item, similar to Windows Explorer.

I thought someone might find this useful...

UniListBox.ClientEvents.ExtEvents ->

function afterrender(sender, eOpts)
{
    var lb = sender,
        store = lb.getStore(),
        field = lb.displayField || 'val';

    lb._searchBuffer = '';

    lb.on('keypress', function(e){

        var ch = e.event.key;

        if (!ch || ch.length !== 1)
            return;

        lb._searchBuffer += ch.toLowerCase();

        Ext.defer(function(){
            lb._searchBuffer = '';
        }, 1000);

        var idx = store.findBy(function(rec){
            var text = rec.get(field);
            return text && text.toLowerCase().startsWith(lb._searchBuffer);
        });

        if (idx !== -1) {
            lb.boundList.getSelectionModel().select(idx);
            lb.boundList.getNavigationModel().setPosition(idx);
        }

    });
}