When used in binding, and the multiple property is set to true proprieade model is null, so do not run this part of the existing code in médodo setMultiple ()

if (_model! = null)
((Selectable) _model). SetMultiple (multiple);

after that will run the following code:

private void doInitRenderer () {
/ / Sync status from the multiple model
if (_model! = null)
setMultiple (((selectable) _model). isMultiple ());

Because of the multiple proprieade DatabindingListModelList default is false. The listbox will never be multiple because the code above will always change the listbox to multiple = false;