GTK3 porting problem (clipboard)

["Miroslav Rajcic" <rajcic sokrates hr>]

I resolved the majority of the the issues when porting my program from GTK 
2.x to GTK 3.x.
Unfortunately I still have one issue left:

when compiling the program on Feodra 15 alpha (gcc 4.6, GTK3 v3.0.2) I get 
these errors:

./src/clipboard.cpp:442:38: error: invalid use of incomplete type 
'GtkTargetList'
/usr/include/gtk-3.0/gtk/gtkselection.h:48:16: error: forward declaration of 
'GtkTargetList'
./src/clipboard.cpp:445:20: error: invalid use of incomplete type 
'GtkTargetList'
/usr/include/gtk-3.0/gtk/gtkselection.h:48:16: error: forward declaration of 
'GtkTargetList'
./src/clipboard.cpp:447:3: error: 'GtkTargetPair' was not declared in this 
scope
./src/clipboard.cpp:447:18: error: 'pair' was not declared in this scope

The relevant code is this:

#include <gtk/gtk.h>

GtkTargetList *list = gtk_target_list_new (NULL, 0);
.. add text and other targets in the list

// LINE 442: error: invalid use of incomplete type 'GtkTargetList'
int nTargetCnt = g_list_length (list->list);

//LINE 445: error: invalid use of incomplete type 'GtkTargetList'
for (GList *l=list->list; l; l=l->next, i++)

//LINE 447: error: 'GtkTargetPair' was not declared in this scope
GtkTargetPair *pair = (GtkTargetPair *)l->data;

This all works fine with GTK2.x.

What is the correct way to work with this on GTK 3.x ?