TYPO3 Core

The Install-Tool callout-box used for Status Messages should support HTML or at least use nl2br to correctly display messages written using $output->writeln() .

With TYPO3 v9+ the Install-Tool support Symfony Input/Output Models and Formatters for interakting with the user. More complex custom wizards giving output-messages are currently ouput without any formatting nor line-breaks in the callout box appearing after running a wizard.

I think it would be a good idea to support HTML formattings here. To archive best compatibility between CLI and Web-Interface there could be an additional Symfony Formatter (WebOutputFormatter) which transforms pure CLI/Text output to HTML formattings.

At least Line-Breaks should be supported using nl2br.

I've tested HTML ouput, but the whole HTML is displayed as text, because InfoBox.js rendering the callout is using .text(message), for correct rendering it would have to use _.html(message.
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