I decided to postpone using GTKExpander until it was available in Glade, but I've made some refinements to msearch-gui nonetheless. I'm using the checkbox to hide and show the clauses. Only the visible clauses will form the query. I spent more time then necessary making gettext friendly label changes for the checkboxes; I've got to stop moving between languages and frameworks. I've got to hook the new editor behavior up the to query generator next.
I'll have a workable Medusa interface soon. Soon I'll start putting this work into Nautilus.