Centralize retained dialog cancel bindings

src/node_dialog_export_ppbr.cpp

@@ -3,6 +3,7 @@
 #include "node_dialog_export_ppbr.h"
 #include "app.h"
 #include "image.h"
+#include "legacy_ui_overlay_services.h"
 
 Node* NodeDialogExportPPBR::clone_instantiate() const
 {
@@ -30,9 +31,7 @@ void NodeDialogExportPPBR::init_controls()
         m_dest_path_txt->SetVisibility(false);
     btn_ok = find<NodeButton>("btn-ok");
     btn_cancel = find<NodeButton>("btn-cancel");
-    btn_cancel->on_click = [this](Node*) {
-        destroy();
-    };
+    pp::panopainter::bind_legacy_click_destroys_node(*btn_cancel, *this);
     btn_header_open = find<NodeButton>("header-open");
     btn_header_open->on_click = [this] (Node*) {
         open_header();