First, please add config options to combobox for anyMatch and caseSensitive, which are passed to the stored queryFilter.

Second, please add code to the top of doQuery for:

if( queryString.length < this.minChars ) {
        forceAll = true;
Because when using field validation (allowBlank: false, forceSelection: true, typeAhead: true), and deleting values typed into the combo box, the full list does not appear (basically forceAll isn't being forced to true).