thank you ! below code can work :
editor.NewFile();
var NewDoc = editor.ActiveDocument;
editor.OpenFile(sFullFn, 0, eeOpenDetectAll); //if goal not open : open inplace; if goal open already : switch to goal document
if (editor.ActiveDocument.FullName != NewDoc.FullName) //empty NewDoc is leftover if goal open already, so close it
NewDoc.close();
but below work in old version (unsure which version)
if (editor.ActiveDocument != NewDoc) ...
so I must modify many code from “doc1 != doc2” to “doc1.FullName != doc2.FullName”
it is incompatible with old version