Please describe the problem:

Hello. We have found anoying problem which occurs when a GtkPaned is
inserted as a page to a GtkNotebook.
When you move your mouse over that handle which is used to adjust
division in GtkPaned and you use your mouse wheel then the page is
changed in the notebook.
Even if this looks ok for someone, this is a major problem for us.
Because we hide pages on the GtkNotebook from users and we don't want to
allow user to change pages when he wants. Of course we use
gtk_notebook_set_show_tabs(notebook, FALSE).
This is a way we implement different screens in Freeciv.

Can anyone help us?
I've attached a simple program, which demonstrates the problem.

--
Freeciv developers

Steps to reproduce:
1.
Compile the following program:
#include <gtk/gtk.h>

int main(int argc, char* argv[])
{
  GtkWidget* window, *notebook, *paned;

  gtk_init(&argc, &argv);  

  window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

  notebook = gtk_notebook_new();
  gtk_container_add(GTK_CONTAINER(window), notebook);
  
  gtk_notebook_append_page(GTK_NOTEBOOK(notebook),
                           gtk_label_new("Page 1"),
			   gtk_label_new("Page 1"));
			   
  paned = gtk_vpaned_new();
  gtk_notebook_append_page(GTK_NOTEBOOK(notebook),
                            paned,
			    gtk_label_new("Page 2"));
  gtk_paned_add1(GTK_PANED(paned), gtk_label_new("Top"));
  gtk_paned_add2(GTK_PANED(paned), gtk_label_new("Bottom"));

  gtk_notebook_append_page(GTK_NOTEBOOK(notebook),
                           gtk_label_new("Page 3"),
			   gtk_label_new("Page 3"));


  gtk_widget_show_all(window);
  gtk_main();
}

2. Run it
3. Switch to the second page
4. Place your mouse over the handler in GtkPaned
5. Use your mouse

Actual results:
The page is changed in GtkNotebook

Expected results:
That the page isn't changed

Does this happen every time?
Yes

Other information: