create a custom tinyMCE template with contao version check

be_tinyMCE.html5

<?php

namespace Contao;

if ($GLOBALS['TL_CONFIG']['useRTE']):

?>
<?php if ( version_compare(VERSION, '4.5', '>=')): ?>
  <script>window.tinymce || document.write('<script src="<?= $this->asset('js/tinymce.min.js', 'contao-components/tinymce4') ?>">\x3C/script>')</script>
<?php else: ?>
  <script>window.tinymce || document.write('<script src="<?= TL_ASSETS_URL ?>assets/tinymce4/js/tinymce.min.js">\x3C/script>')</script>
<?php endif; ?>
<script>
setTimeout(function() {
  window.tinymce && tinymce.init({
    skin: 'contao',
    selector: '#<?= $this->selector ?>',
    language: '<?= Backend::getTinyMceLanguage() ?>',
    element_format: 'html',
    document_base_url: '<?= Environment::get('base') ?>',
    entities: '160,nbsp,60,lt,62,gt,173,shy',
    setup: function(editor) {
      editor.getElement().removeAttribute('required');
    },
    init_instance_callback: function(editor) {
      if (document.activeElement && document.activeElement.id && document.activeElement.id == editor.id) {
        editor.editorManager.get(editor.id).focus();
      }
      editor.on('focus', function(){ Backend.getScrollOffset(); });
    },
    file_browser_callback: function(field_name, url, type, win) {
      Backend.openModalBrowser(field_name, url, type, win);
    },
    branding: false,
    plugins: 'autosave charmap code fullscreen image importcss link lists paste searchreplace tabfocus table visualblocks',
    browser_spellcheck: true,
    tabfocus_elements: ':prev,:next',
    importcss_append: true,
    extended_valid_elements: 'q[cite|class|title],article,section,hgroup,figure,figcaption',
    menubar: 'file edit insert view format table',
    toolbar: 'link unlink | image | bold italic | styleselect | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | undo redo | code',
    content_css: ['/files/theme/dist/css/tinymce.css'],
    style_formats_merge: true,
    style_formats: [
	  	{title: 'Theme Styles', items: [
	  		{ title: 'Button Primary', block: 'div', classes: 'btn btn--primary', exact: true },
	  		{ title: 'Button Secondary', block: 'div', classes: 'btn btn--secondary',  exact: true },
	  		{ title: 'Text Attention', block: 'p', classes: 'text--attention',  exact: true }
	  	]}
    ]
  });
}, 0);
</script>
<?php endif; ?>