+ update();
+}
+
+void Header::on_group()
+{
+ vector< shared_ptr<RowItem> > selected_items(
+ make_filter_iterator(item_selected, view_.begin(), view_.end()),
+ make_filter_iterator(item_selected, view_.end(), view_.end()));
+ stable_sort(selected_items.begin(), selected_items.end(),
+ [](const shared_ptr<RowItem> &a, const shared_ptr<RowItem> &b) {
+ return a->visual_v_offset() < b->visual_v_offset(); });
+
+ shared_ptr<TraceGroup> group(new TraceGroup());
+ shared_ptr<RowItem> mouse_down_item(
+ std::dynamic_pointer_cast<RowItem>(mouse_down_item_));
+ shared_ptr<RowItem> focus_item(
+ mouse_down_item ? mouse_down_item : selected_items.front());
+
+ assert(focus_item);
+ assert(focus_item->owner());
+ focus_item->owner()->add_child_item(group);
+
+ // Set the group v_offset here before reparenting
+ group->force_to_v_offset(focus_item->layout_v_offset() +
+ focus_item->v_extents().first);