add xml attributes for combobox node and add resolution selection for new doc

engine/node_dialog_open.h

@@ -4,6 +4,7 @@
 #include "node_image_texture.h"
 #include "node_text.h"
 #include "node_text_input.h"
+#include "node_combobox.h"
 
 class NodeDialogOpenItem : public NodeBorder
 {
@@ -65,6 +66,7 @@ public:
     NodeButton* btn_cancel;
     NodeButton* btn_ok;
     NodeTextInput* input;
+    NodeComboBox* m_resolution;
     virtual Node* clone_instantiate() const override;
     virtual void clone_finalize(Node* dest) const override;
     virtual void init() override;