I don't know if it's more a bug or a wanted feature. Probably more a wanted feature : it would be nice to have the Creole syntax in conditionnal, as we have it in regular nodes :
In conditionnal :
if (= my heading graphviz installed?\n----* Bullet list
* Second item
** Sub item)
could work exactly as in normal node :
:= my heading graphviz installed?\n----* Bullet list
* Second item
** Sub item;
except ... the frame is not the same.