gfio: make notebooks scrollable if there are too many

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/gfio.c b/gfio.c
index 52389be..3cd6149 100644
--- a/gfio.c
+++ b/gfio.c
@@ -2394,6 +2394,7 @@
 
 	ui->notebook = gtk_notebook_new();
 	g_signal_connect(ui->notebook, "switch-page", G_CALLBACK(notebook_switch_page), ui);
+	gtk_notebook_set_scrollable(GTK_NOTEBOOK(ui->notebook), 1);
 	gtk_container_add(GTK_CONTAINER(ui->vbox), ui->notebook);
 
 	vbox = new_main_page(ui);