onDidLayoutChange callback catches panels init

[artaommahe]

Describe the bug

onDidLayoutChange callback is triggered after panels were initialised inside onReady callback despite callback being registered after adding panels.

To Reproduce

Steps to reproduce the behavior:

1. Go to https://stackblitz.com/edit/vitejs-vite-6lyqey?file=src%2FApp.tsx
2. See triggered onDidLayoutChange in the console

Expected behavior

onDidLayoutChange should be triggered only on following layout changes

Screenshots

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Desktop (please complete the following information):

• Browser Chrome on Mac
• Version 124.0.6367.119

Additional context

As i see in debugger layout changes are fired through Emitter that triggers callbacks inside a setTimeout, looks like that's the reason why a onDidLayoutChange callback registered after adding panels catches those changes as a layout change.

We're implementing saving the layout to the database and for now have to bypass this behaviour with wrapping onDidLayoutChange listener with a setTimeout that doesn't look stable and relies on Emitter's behaviour.

[mathuo]

Thanks for the details description and analysis of the source code.

I have now made the required changes for this to work correctly and it is released in 1.13.1