ext_tables.php

<?php
defined('TYPO3_MODE') or die();

// Add Abbreviation records
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::allowTableOnStandardPages('tx_rtehtmlarea_acronym');
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addLLrefForTCAdescr('tx_rtehtmlarea_acronym', 'EXT:rtehtmlarea/Resources/Private/Language/locallang_csh_abbreviation.xlf');

// Add contextual help files
$htmlAreaRteContextHelpFiles = [
    'General' => 'EXT:rtehtmlarea/Resources/Private/Language/locallang_csh.xlf',
    'Abbreviation' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/Abbreviation/locallang_csh.xlf',
    'EditElement' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/EditElement/locallang_csh.xlf',
    'Language' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/Language/locallang_csh.xlf',
    'MicrodataSchema' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/MicrodataSchema/locallang_csh.xlf',
    'PlainText' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/PlainText/locallang_csh.xlf',
    'RemoveFormat' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/RemoveFormat/locallang_csh.xlf',
    'TableOperations' => 'EXT:rtehtmlarea/Resources/Private/Language/Plugins/TableOperations/locallang_csh.xlf'
];
foreach ($htmlAreaRteContextHelpFiles as $key => $file) {
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addLLrefForTCAdescr('xEXT_rtehtmlarea_' . $key, $file);
}
unset($htmlAreaRteContextHelpFiles);

if (TYPO3_MODE === 'BE') {
    $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['RteImageSelector']['hooks']['editImageHandler'] = [
        'handler' => \TYPO3\CMS\Rtehtmlarea\ImageHandler\EditImageHandler::class
    ];
}

// Extend TYPO3 User Settings Configuration
if (TYPO3_MODE === 'BE' && \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::isLoaded('setup') && is_array($GLOBALS['TYPO3_USER_SETTINGS'])) {
    $GLOBALS['TYPO3_USER_SETTINGS']['columns'] = array_merge($GLOBALS['TYPO3_USER_SETTINGS']['columns'], [
        'rteWidth' => [
            'type' => 'text',
            'label' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang.xlf:rteWidth',
            'csh' => 'xEXT_rtehtmlarea_General:rteWidth'
        ],
        'rteHeight' => [
            'type' => 'text',
            'label' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang.xlf:rteHeight',
            'csh' => 'xEXT_rtehtmlarea_General:rteHeight'
        ],
        'rteResize' => [
            'type' => 'check',
            'label' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang.xlf:rteResize',
            'csh' => 'xEXT_rtehtmlarea_General:rteResize'
        ],
        'rteMaxHeight' => [
            'type' => 'text',
            'label' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang.xlf:rteMaxHeight',
            'csh' => 'xEXT_rtehtmlarea_General:rteMaxHeight'
        ],
        'rteCleanPasteBehaviour' => [
            'type' => 'select',
            'renderType' => 'selectSingle',
            'label' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/Plugins/PlainText/locallang_js.xlf:rteCleanPasteBehaviour',
            'items' => [
                'plainText' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/Plugins/PlainText/locallang_js.xlf:plainText',
                'pasteStructure' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/Plugins/PlainText/locallang_js.xlf:pasteStructure',
                'pasteFormat' => 'LLL:EXT:rtehtmlarea/Resources/Private/Language/Plugins/PlainText/locallang_js.xlf:pasteFormat'
            ],
            'csh' => 'xEXT_rtehtmlarea_PlainText:behaviour'
        ]
    ]);

    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addFieldsToUserSettings(
        '--div--;LLL:EXT:rtehtmlarea/Resources/Private/Language/locallang.xlf:rteSettings,rteWidth,rteHeight,rteResize,rteMaxHeight,rteCleanPasteBehaviour'
    );
}