fxff

// gtk-method-patching.c: an example of patching GTK methods. 
// gcc `pkg-config --libs --cflags gtk+-3.0` gtk-method-patching.c 

#include <gtk/gtk.h>

typedef void (* get_preferred_width) (GtkWidget *, gint *, gint *);

get_preferred_width original; // A place to store real function

void patched_gpw (GtkWidget *w, gint *min_w, gint *nat_w)

fxff

#include <stdio.h>

typedef struct {
  int foo;
  int bar;
} A;
typedef struct {
  char foo;
  char bar;
} B;