I'm looking at this page on GitHub with the source code to build your own text editor.
I want a text editor for movie script writing.
What can I use for this purpose on Ubuntu?
Amazon Storywriter is a free screenwriting tool distributed by Amazon as a web application for Google Chrome and Chromium web browser. This app can be used offline even when there is no connection to the internet.
Storywriter automatically formats your screenplay as you type - you don't need to tell Storywriter what kind of element you want to use. Each element gets formatted when you move to the next line.