DropDownByIndex and structured Node

Hi,

I have defined a structure with a field display of type string.

I create a context node from that structure so that I have a node attribute

named display of type my_struct-DISPLAY

Problem is that I would like to display this attribute in a dropdownbyindex but when I want to bind the text, my attribute is grayed so I cannot select it.

Is this a bug ? How can I display in a dropdownByIndex an attribute coming from a dictionary structure.

Thanks,

Thierry