Speaking of "require"s, could we perhaps export which reqires that are enabled to the cpp somehow, so that you can test for them in the pike code as well? Case in point; the GTK2 version of Tools.PV wants to use GTK2.Widget()->get_window(), which requires gtk 2.14, but I have no way of testing if it exists, which led to the testsuite failing on some xenofarm machine (I forget which) that had an older GTK2.