You could create a special wide theme (so that posts occupy 50-60% of the FHD-2K-4K screen width; currently, 30% is too little) for the tree view, so that frequent users can enable it. Or, even better, create two different themes for flat and tree views. I thought the Foundation theme (full-width) should do this, but for some reason, the main width with posts ( <div class="nested-view"> ; <div class="post__row row"> , I found the right way to do this How to increase width of topic - #7 by awesomerobot , but I would like to just choose a theme, without use custom UserStyle) doesn’t increase.
I came up with an improvement to my idea: clicking this button opens the ENTIRE chain of related posts, not in a new tab, but as a block on the right. And everything fits the screen width: on the left is a 10% navigation block, as it currently is, next to it is a 30% block of posts, as it currently is (can be increased to 40%), and on the right is a 50% block in which the nested/threaded ENTIRE chain of related posts will open.
I’ll also ask other participants to respond with some long messages and create 10 levels of nesting to see how it looks, including on a phone.