setCanDragSelectText not works in IE11

I am using smartgwtpro 4.1.b20150227

I have called these two methods for a listgrid, however, select & copy works in Chrome, but not works in IE11

setCanSelectText(true);
setCanDragSelectText(true);


well, I also tested smartclient version in demo page (http://www.smartclient.com/#columnOrder ) by :

canSelectText:true,
canDragSelectText : true,


it works in Chrome, but failed in IE11 too