Enable the GncTreeView to track the grid line preferences

With these changes when the preferences for showing horizontal or
vertical grid lines are changed it will update the GncTreeView
immediately.

gnucash/gnome-utils/gnc-tree-view.c

@@ -44,6 +44,7 @@
 #include "gnc-gobject-utils.h"
 #include "gnc-cell-renderer-date.h"
 #include "gnc-state.h"
+#include "gnc-prefs.h"
 #include "dialog-utils.h"
 
 /* The actual state key for a particular column visibility.  This is
@@ -223,6 +224,13 @@ gnc_tree_view_class_init (GncTreeViewClass *klass)
     gtkwidget_class->destroy = gnc_tree_view_destroy;
 }
 
+static void
+gnc_tree_view_update_grid_lines (gpointer prefs, gchar* pref, gpointer user_data)
+{
+    GncTreeView *view = user_data;
+    gtk_tree_view_set_grid_lines (GTK_TREE_VIEW(view), gnc_tree_view_get_grid_lines_pref ());
+}
+
 /** Initialize a new instance of a base gnucash tree view.  This
  *  function allocates and initializes the object private storage
  *  space.  It also adds the new object to a list (for memory tracking
@@ -274,6 +282,10 @@ gnc_tree_view_init (GncTreeView *view, GncTreeViewClass *klass)
 
     // Set grid lines option to preference
     gtk_tree_view_set_grid_lines (GTK_TREE_VIEW(view), gnc_tree_view_get_grid_lines_pref ());
+    gnc_prefs_register_cb (GNC_PREFS_GROUP_GENERAL, GNC_PREF_GRID_LINES_HORIZONTAL,
+                           gnc_tree_view_update_grid_lines, view);
+    gnc_prefs_register_cb (GNC_PREFS_GROUP_GENERAL, GNC_PREF_GRID_LINES_VERTICAL,
+                           gnc_tree_view_update_grid_lines, view);
 
     /* Create the last column which contains the column selection
      * widget.  gnc_tree_view_add_text_column will do most of the
@@ -348,6 +360,11 @@ gnc_tree_view_destroy (GtkWidget *widget)
 
     view = GNC_TREE_VIEW (widget);
 
+    gnc_prefs_remove_cb_by_func (GNC_PREFS_GROUP_GENERAL, GNC_PREF_GRID_LINES_HORIZONTAL,
+                                 gnc_tree_view_update_grid_lines, view);
+    gnc_prefs_remove_cb_by_func (GNC_PREFS_GROUP_GENERAL, GNC_PREF_GRID_LINES_VERTICAL,
+                                 gnc_tree_view_update_grid_lines, view);
+
     priv = GNC_TREE_VIEW_GET_PRIVATE(view);
 
     if (priv->state_section)