So i follow this tutorial -> https://magento.marcelhauri.ch/blog/how-to-add-a-tinymce-plugin-to-the-magento2-wysiwyg-editor
And everything works so far if i remove this line of code
ed.contentCSS = [ed.settings.magentoPluginsOptions._object.Addfourcolumnbox.css];
But if i add it i get an error that say this
Failed to initialize plugin: Addfourcolumnbox TypeError: Cannot read property 'Addfourcolumnbox' of undefined at t.<computed>.t.<computed>.init
So i have tried everything to fix it, but nothing works, so i hope somebody else have dealt with the same problem before me and found a answer to it.