ext_localconf.php

<?php
if (!defined('TYPO3_MODE')) {
    die('Access denied.');
}

// Configure frontend plugin
\TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin(
    'Heilmann.' . $_EXTKEY,
    'Pi1',
    array(
        'Magnificpopup' => 'show'
    ),
    array(
    )
);

// Save the IRRE content (use hook to change colPos)
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['processDatamapClass'][$_EXTKEY] = 'EXT:'.$_EXTKEY.'/Classes/Hooks/class.tx_jhmagnificpopup_tcemain.php:&tx_jhmagnificpopup_tcemain';

// Page TSconfig for global enabled iframe
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPageTSConfig('
	RTE.classesAnchor {
	  externalLinkInMagnificpopup {
	    class = mfp-link external-link-new-window
	    type = url
	    image >
	    titleText = LLL:EXT:jh_magnificpopup/Resources/Private/Language/locallang.xlf:pageTSconfig.externalLinkInMagnificpopup
	  }
	  internalLinkInMagnificpopup {
	    class = mfp-link internal-link-new-window
	    type = page
	    image >
	    titleText = LLL:EXT:jh_magnificpopup/Resources/Private/Language/locallang.xlf:pageTSconfig.internalLinkInMagnificpopup
	  }
	  downloadInMagnificpopup {
	    class = mfp-link download
	    type = file
	    image >
	    titleText = LLL:EXT:jh_magnificpopup/Resources/Private/Language/locallang.xlf:pageTSconfig.downloadInMagnificpopup
	  }
	}

	RTE.default.proc.allowedClasses := addToList(mfp-link external-link-new-window, mfp-link internal-link-new-window, mfp-link download)
	RTE.default.classesAnchor := addToList(mfp-link external-link-new-window, mfp-link internal-link-new-window, mfp-link download)

	RTE.default.buttons.link.properties.class.allowedClasses := addToList(mfp-link external-link-new-window, mfp-link internal-link-new-window, mfp-link download)
');

// Add eID for ajax-content
$GLOBALS['TYPO3_CONF_VARS']['FE']['eID_include']['jh_magnificpopup_ajax'] = 'EXT:'.$_EXTKEY.'/Resources/Public/Php/EidRunner.php';


//
// alpha-features::
//
$extConfig = unserialize($GLOBALS['TYPO3_CONF_VARS']['EXT']['extConf']['jh_magnificpopup']);
if (isset($extConfig['enableAlphaFeatures']) && $extConfig['enableAlphaFeatures'] == 1) {
    \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPageTSConfig('
		RTE.classesAnchor {
		  internalCEInMagnificpopup {
		    class = mfp-content-element internal-link-new-window
		    type = page
		    image >
		    titleText = LLL:EXT:jh_magnificpopup/Resources/Private/Language/locallang.xlf:pageTSconfig.internalCEInMagnificpopup
		  }
		}

		RTE.default.proc.allowedClasses := addToList(mfp-content-element internal-link-new-window)
		RTE.default.classesAnchor := addToList(mfp-content-element internal-link-new-window)

		RTE.default.buttons.link.properties.class.allowedClasses := addToList(mfp-content-element internal-link-new-window)
	');
}