Hi there. I followed the video here Developing a Text Editor, part 1 - YouTube on creating a text editor but I am stuck since I want to go an alternative route.
I don’t want the controls in a different window or preferences pane, I want the font controls on the same window like MS word which would automatically change the text document fonts. How can I achieve this?
you could use a container control and drop all controls you need inside.
your container control is then placed together with the textarea in the same window.
define events/raise events and change selected text by a method inside of the cc.
You may want to read this book (examples from the book are provided with the download archive):
https://www.xojo.com/resources/learn.php
And… all the commands you saw in a “different window” or in a “preferences pane” can be placed in your wndow instead. t is just a matter of where you place the controls, not how you code the stuff…
Nota: MS Word also have windows to moficy the Fonts, Size, Paragraph and Page Properties, etc. (not only what you see in the front window) 
Thanks for the information guys. 