I've been working with a variety of themes over the last 3 years, and I have often felt like I needed a quickly accessible spot where I can access common code/shortcode for copying and pasting.
I'd like to suggest a drawer that functions similarly to a toggle that carries text throughout the admin interface by user, so that if someone wants to access common code, it will always be there, without necessitating a different application, page, or leaving what you are working on. Not sure if that is practical or something that other people would want, but I think it has a lot of potential as a feature. Maybe someone ambitious would do a plug-in, but I think it would function better as an integrated feature.
Thanks for listening!