Keep the view when switching mode reading->editing

[WhiteNoise]

First switch from Reading mode -> Editor incorrectly opens document from the beginning

It is the same as this bug, except I found a consistent way to reproduce it on my machine. Reproduction guide: Switch from one file to other, long, file. Make sure the file you’re switching to opens in reading mode (if it opens in editing mode, do so by toggling to reading mode, and then switching to other file and back, such that it reopens in reading mode). Switching to reading mode after the file is already open doesn’t reproduce the bug. Then scroll down enough, so the jump to the top of t…