onDidChangeActiveTextEditor always reports active selection of 0,0 · Issue #136618 · microsoft/vscode (original) (raw)

Does this issue occur when all extensions are disabled?: Bug is about extension API

• VS Code Version: 1.61
• OS Version: Ubuntu 20.04.3 LTS

When a user opens a new file at any position other than (0,0) (for example, by using Go to definition), onDidChangeActiveTextEditor will report (0,0) until the onDidChangeTextEditorSelection reaches the extension host. An extension that wants to act on the active selection has to implement a waiting logic similar to

onDidChangeActiveTextEditor(document => {
  // Wait a short period until an optional selection update reaches the extension host
  setTimeout(() => {
    // Execute logic here
  }, 500);
}

Needless to say that this is a brittle workaround, but I cannot think of any else, because the onDidChangeTextEditorSelection is not triggered if the document is opened at (0,0).

Out of curiosity, I dug around the source code to understand where the problem is coming from. Here is my understanding: In textFileEditors.ts, the onDidChangeActiveTextEditor event is triggered by updating the text model:

textEditor.setModel(textFileModel.textEditorModel);

The selection is updated shortly afterwards:

applyTextEditorOptions(options, textEditor, ScrollType.Immediate);

Flipping these statements around is not enough, because the selection is internally transported by an event and will not reach the code that generates the event that is sent to the extension host in time.