conditional os in UI xml, add system dialog file open on osx, check api format or error message when opening a document, per-char text wrap on NodeText, additional info on create doc dialog like working path

src/node_dialog_open.h

@@ -66,6 +66,7 @@ public:
     NodeButton* btn_cancel;
     NodeButton* btn_ok;
     NodeTextInput* input;
+    NodeText* working_path;
     NodeComboBox* m_resolution;
     virtual Node* clone_instantiate() const override;
     virtual void clone_finalize(Node* dest) const override;