Hello, I have following structure:

    typedef struct
{
 GtkWidget* PoziomaLinijka;
 GtkWidget* PionowaLinijka;
 GtkWidget* Label1;
 GtkWidget* Label2;
 gint x,y;
} StrukturaDrawing;

And i need to allocate it on the heap because later I have functions which uses that structure and I don't want to use global variables. So I allocate it like this:

    StrukturaDrawing* Wsk;
  Wsk = (StrukturaDrawing*)malloc(sizeof(StrukturaDrawing));
  if (!Wsk)
  {
 printf("Error\n");
  }

And it doesn't returning error and also works great with other functions, it works the way I wanted it to work so finally i wanted to free that memory and here is problem because in Debug Mode compilator bitches:

First-chance exception at 0x102d12b4 in GTK.exe: 0xC0000005: Access violation reading location 0xfffffffc. Unhandled exception at 0x102d12b4 in GTK.exe: 0xC0000005: Access violation reading location 0xfffffffc.

I connect callback to my function, like that:

g_signal_connect(G_OBJECT(Okno), "destroy", G_CALLBACK(Wyjscie), Wsk);

Function which is suppose to free memory and close program:

void Wyjscie(GtkWindow* window, GdkEvent* event, StrukturaDrawing* data)
{
 gtk_main_quit();
 free(data);
 data = NULL;
}

Any help really appreciated.