How to trigger custom URL scheme calls in an IAB window opened with _blank?

AFAIK URLs opened with `'_blank'` cannot trigger custom URL scheme calls, meaning that if the website I just opened would try to call back my app using `"myapp://"` but would fail because that browser doesn't grant this capability.

on the other hand, URLs opened with `'_system'` do enjoy this functionality, but sadly cannot be closed after ending their task with `"ref.close()"`.

there is no point of having a `close()` method when the browser cannot provide feedback to the app.. when should the app know to close the browser? it can't even can't receive any kind of feedback using `'_blank'`.

How can I work around this?

Reproduce the reported behavior for InAppBrowser windows opened with `_blank` and `_system`, focusing on custom `myapp://` scheme calls and `ref.close()`. The issue does not name implementation files or tests; done would require a documented, reproducible way to receive feedback and close the browser, or a confirmed explanation of the platform limitation.

Written by the indexing model from the issue text.