- Electron version: 0.37.6
- Operating system: Windows 10

In VSCode, in order to support screen readers while editing text, we set the contents of a `<textarea>` to the contents of the line and lines surrounding the cursor and we mirror the editor selection in the `<textarea>` via `setSelectionRange`.

Chromium is not the fastest when it comes to setting large amounts of text :) (such as > 10,000 characters) and basically stalls all the time. Apparently, Electron already has some knowledge about when a screen reader is attached to the main process window (in C++ code). Is it possible to expose this as a getter + event when it first happens in the `electron` API.

We could then maintain this costly `<textarea>` sync only when really needed.

atom/browser/api/atom_api_app.cc
App::App(v8::Isolate* isolate) {
  static_cast<AtomBrowserClient*>(AtomBrowserClient::Get())->set_delegate(this);
  Browser::Get()->AddObserver(this);
  content::GpuDataManager::GetInstance()->AddObserver(this);
  Init(isolate);
}
App::~App() {
  static_cast<AtomBrowserClient*>(AtomBrowserClient::Get())->set_delegate(
      nullptr);
  Browser::Get()->RemoveObserver(this);
  content::GpuDataManager::GetInstance()->RemoveObserver(this);
}
void App::OnBeforeQuit(bool* prevent_default) {
  *prevent_default = Emit("before-quit");
}
void App::OnWillQuit(bool* prevent_default) {
  *prevent_default = Emit("will-quit");
}
void App::OnWindowAllClosed() {
  Emit("window-all-closed");
}
void App::OnQuit() {
  int exitCode = AtomBrowserMainParts::Get()->GetExitCode();
  Emit("quit", exitCode);
  if (process_singleton_.get()) {
    process_singleton_->Cleanup();
    process_singleton_.reset();
  }
}
void App::OnOpenFile(bool* prevent_default, const std::string& file_path) {