There are distraction-free text editors (for example, the ones cited here) that have full-screen editing area and minimum user interface. Is there any objective statistics showing whether these actually decrease distraction? What are the most effective design features in text editors to decrease distraction or increase productivity?
A few suggestions I'd have for distraction-free, or user-friendly, text writing UIs:
• Tall text field
Longform text fields, like the one I'm using to reply to you, provide an inherent white space - so making this field sufficiently tall to feel spacious would be the first step. One helpful additional feature is an expandable text field, as this one on StackExchange has.
• Kitchen sink controls
Sorry, minimalists, but you'll need some formatting controls if you want your text editing tool to be taken seriously. Evernote's is useful, yet with a light footprint:
To be a minimalist designer of formatting controls, get rid of ones that don't matter, and use recognized, simple iconography.
• Built-in below-last-line padding
If you want to feel uncluttered and in control, build in a floor that is high above the bottom of whatever window your text field is floating in. Give a sense to the user that there is still space ahead/in the future/yet to come/below their text. Many writing tools forget this important spatial affordance.
This is even more important in a mobile interface, where the keypad UI is going to fill nearly half the screen.
• Built-in side padding
Similarly, give some space on the sides that has no text or elements. Even a thin line can feel like a brick wall. In designing layout, I always see if the visual cues hold after I remove the boxes and outlines.
• Last Point
My only other point is that "distraction-free" is a bit of a silly notion. Modern humans are very good at dismissing and ignoring things that do not matter to them. I read a news article online and do not absorb any advertisement. I type something, and I am focused on the text field only. If you are getting distracted by stuff surrounding your writing tool, I argue that beyond flashing GIF ads, it is not at all about the sidebars or background. It's all about the spaciousness of the text field and the access of controls.