Edittext field with rounded corners

Is it possible to create rounded edittext field on dialog box or it must be rectangle? 

var box = new Window("dialog","TEST");
box.group = box.add('group', undefined); 
box.group.orientation='row';  
box.group.alignment = 'left';
box.group.text = box.group.add('statictext', [25,40,75,60],"Test");
var testvalue = box.group.add('edittext', [25,40,75,60]);
box.show()