[galaxy-dev] Tool's xml: conditionals

Is it possible to have not-strictly-hierarchical conditionals in a tool's xml file?

I would like to have a parameter being available depending on the state of another (previously defined) condition:

<conditional name="c1"> <param name="c1" type="boolean"... </conditional> <conditional name="c2"> <param name="c2" type="boolean"... <when name="c1" value="true" ... <when name="c2" value="true" ... ... </when> ... </when> ... </conditional>

According to the current documentation this doesn't seem to be supported in any obvious way.