Thanks for your answer, Ugo, I only do not get your point.
My problem was about binding and I solved it with the above wb:javascript code and it works for the moment. But I could imagine that I'm not the only one binding selection lists to a collection, so maybe adding an element like the above mentioned wb:list could replace the need for the wb:javascript above. It's like the sample on the wiki - instead you can simply use wb:value.
Pardon me if I'm being obtuse, but why would you want to set a selection list's contents via binding? Isn't your aim to generate the <option>s of a <select> using a collection? If so, what is the flow-jxpath selection list missing? Or is it me that is missing something obvious here? Can you describe your use case?
Now what should @type="flow-jxpath" change, especially as it is in the form definition? setSelectionList() also works without specifying the @type, even without having wd:selection-list in the form definition.
Not it's me that's not getting your point here ;-).
Ugo