Hi,
vala does not create code that humans would write for reference handling and is rather hard to read.

For example:
return (__temp0 = 0, (sample == NULL ? NULL : (sample = (g_object_unref (sample), NULL))), __temp0);
(sample == NULL ? NULL : (sample = (g_object_unref (sample), NULL)));

A human would probably write this with if, else, etc.

Every other part of generated code is perfectly readable though, good work :)

Bye

PS: the two example lines are taken from the code generated from the Gtk sample. I wonder why there is an expression after the return, it's never called anyway?