Adjust the window layout dynamically based on Window size
If I'm viewing a single document on a widescreen monitor then I have loads of space at the side for Navigation view and other sidebars. However, if I then want to view two documents side-by-side, I end up with no space to see the document unless I close all of the sidebars. Then I have to select to view them again when I go back to viewing a single document on screen.
The suggestion is to make Word work like a modern website, with sidebars shrinking or hiding themselves when the window width is too narrow to display them and see your document.