TextItem changed function not trigger when characterCasing is set ?

SmartClient_v100p_2015-06-20_LGPL

TextItem with/has characterCasing: isc.TextItem.DEFAULT

When any TextItem with characterCasing set to isc.TextItem.UPPER or isc.TextItem.LOWER,
then TextItem changed: function(form, item, value) will not trigger ???

Possible bug ? or any workaround ?