Custom editor button (works with visual but not text editor)

I managed to create a custom editor button for the visual editor (following this tutorial https://code.tutsplus.com/tutorials/guide-to-creating-your-own-wordpress-editor-buttons–wp-30182 )

Is it possible to also add that button to the non-visual aka text editor? And if so, how is it done? (My client will use the visual editor, while I prefer the text editor. So i’d like to have the custom button in both editor views.)

I pretty much used the code from the tutsplus link, just changed <span class=”dropcap”> to <div class=”text-columns”> (so I’m not going to paste any code here)

Thanks!