How can I use a label with "control"-attribute in a binding?

[Markus]

I'm trying to wrap some input fields with their respective label in a
binding.
I wrote the following:

<binding id="tboolean">
<content>
<xul:label xbl:inherits="value=label" control="field"/>
<xul:textbox id="field" xbl:inherits="value,disabled,tooltip" />
</content>
</binding>

When I try to use the new element repeatedly in my XUL-document and
click any label, the focus will always go to the very first element in
the document, instead of going to the corresponding textbox.

As far as I know, I'm not even supposed to use id's in bindings, but the
"control"-attribute needs one. Since this is not the most complicated
binding, nor a very special use-case I must have overlooked something..

Maybe someone can point me in the right direction?

Thanks in advance,
Markus