listbase: Make sure items are in rubberband before adding

The current implementation of get_items_in_rect uses the
item's coordinates to decides whether an item is in the
rubberband's rectangle or not.  This is usually fine,
except if the widget is not the same size as the list item
(i.e. if there are margins around the widget).  The widget is
visible to the user (not the item), so let's make sure that
the widget is really inside of the rubberband.

Fixes: https://gitlab.gnome.org/GNOME/nautilus/-/issues/2436

gtk/gtklistbase.c

@@ -1578,12 +1578,32 @@ gtk_list_base_stop_rubberband (GtkListBase *self,
       GtkBitset *selected, *mask;
       GdkRectangle rect;
       GtkBitset *rubberband_selection;
+      guint pos;
 
       if (!gtk_list_base_get_rubberband_coords (self, &rect))
         return;
 
       rubberband_selection = gtk_list_base_get_items_in_rect (self, &rect);
 
+      pos = 0;
+      for (item = gtk_list_item_manager_get_first (priv->item_manager);
+           item != NULL;
+           item = gtk_rb_tree_node_get_next (item))
+      {
+        if (item->widget)
+          {
+            GtkAllocation widget_allocation;
+            /* Make sure we are actually selecting the widget (i.e. if it has margins) */
+            gtk_widget_get_allocation (item->widget, &widget_allocation);
+
+            if (gtk_bitset_contains (rubberband_selection, pos) &&
+                !gdk_rectangle_intersect (&rect, &widget_allocation, NULL))
+              gtk_bitset_remove (rubberband_selection, pos);
+          }
+
+        pos += item->n_items;
+      }
+
       if (modify && extend) /* Ctrl + Shift */
         {
           if (gtk_bitset_is_empty (rubberband_selection))
@@ -1662,7 +1682,12 @@ gtk_list_base_update_rubberband_selection (GtkListBase *self)
     {
       if (item->widget)
         {
-          if (gtk_bitset_contains (rubberband_selection, pos))
+          GtkAllocation widget_allocation;
+          /* Make sure we are actually selecting the widget (i.e. if it has margins) */
+          gtk_widget_get_allocation (item->widget, &widget_allocation);
+
+          if (gtk_bitset_contains (rubberband_selection, pos) &&
+              gdk_rectangle_intersect (&rect, &widget_allocation, NULL))
             gtk_widget_set_state_flags (item->widget, GTK_STATE_FLAG_ACTIVE, FALSE);
           else
             gtk_widget_unset_state_flags (item->widget, GTK_STATE_FLAG_ACTIVE);