TYPO3 Core

The value is in typo3/sysext/filelist/Classes/FileList.php:

    /**
     * Max length of strings
     *
     * @var int
     */
    public $fixedL = 30;

and in typo3/sysext/filelist/Resources/Private/Templates/FileList/Search.html:

{file.name->f:format.crop( maxCharacters:30 )}

I think it would be better, to use css (text-overflow: ellipsis) for that.

On latest master (8.7.1-dev):

- typo3/sysext/filelist/Classes/FileList.php still contains the lines cited on the previous comment

- ypo3/sysext/filelist/Resources/Private/Templates/FileList/Search.html has no more the f:format.crop viewhelper