@stof thanks a lot for the through review!

• I fixed most of the issues that you pointed
• About adding BC support for previous values, it's not worth it. The worst-case scenario is that someone had the toolbar closed an, after updating Symfony, the toolbar will be displayed. This is fine. Just click again on the close button.
• Also, about close/open not being the same as show/hide ... it's true. But these changes don't modify the current behavior. The close/open buttons have been merged into a single toggle button which is always visible.

This is how it works on my local machine:

@javiereguiluz it does change the existing behavior. In 7.1, we have 3 different state:

• hidden toolbar, used while the Ajax request loading it is running
• closed toolbar
• opened toolbar

Your PR shows a closed toolbar during loading (and if loading fails, this will be quite confusing)

In my second commit I changed the default so the toolbar is visible by default. Would that be enough?

I've rebased this to Symfony 7.3 during the #SymfonyHackday of SymfonyCon 2024.

Thank you@javiereguiluz.