Centralize retained panel popup attachment

src/node_panel_brush.cpp

@@ -4,6 +4,7 @@
 #include "assets/brush_package.h"
 #include "app_core/brush_ui.h"
 #include "legacy_brush_ui_services.h"
+#include "legacy_ui_overlay_services.h"
 #include "asset.h"
 #include "texture.h"
 
@@ -579,7 +580,7 @@ void NodePanelBrushPreset::init()
     m_btn_menu->on_click = [this](Node* b) {
         auto popup = add_child_file<NodePopupMenu>("data/dialogs/panel-brushes.xml", "tpl-brush-popup");
         popup->SetPosition(b->m_pos.x + b->m_size.x, b->m_pos.y);
-        root()->add_child(popup);
+        (void)pp::panopainter::attach_legacy_overlay_node_to_root(*this, popup);
         root()->update();
         auto bounds = root()->GetSize() - zw(popup->get_children_rect());
         popup->SetPosition(glm::clamp(popup->m_pos, { 0, 0 }, bounds));