The check for gtk2 in configure.ac is wrong: it checks gtk >= 2.2.0 but it
should be at least 2.10.0 (because some of the API function are not available
before 2.10 : GTK_STOCK_SELECT_ALL, GTK_ASSISTANT ... I didn't verify all calls
but as I'm trying to compile gpa on cygwin I had this problem of unknown functions).

I made a ridiculous small patch for this...