Bring back the overlay scrollbar
Bring back the overlay scrollbar around the main text edition area (the GtkTextView).
commit 5e0909c1 changed the overlay scrollbar into a normal scrollbar (see the explanation in the commit message).
The HIG recommends to use overlay scrollbars, especially for all core GNOME apps.
A solution is to add a margin or padding so that the overlay scrollbar, when appearing, hides the margin/padding and not the text.
Question: has the problem already been solved in another application? I have not tried if the above solution is easy to implement or not, I can give it a try. A generic solution would be useful, not only for GtkTextView, because the problem exists elsewhere, and in other apps as well.
In gedit the overlay scrollbar gets in the way also for the integrated file browser in the side panel, when there is a long list of files, the bottom scrollbar hides the last item in the list. In that case the widget inside the GtkScrolledWindow is a GtkTreeView. I'm sure there are many other examples where the overlay scrollbar gets in the way in gedit.
So maybe a subclass of GtkScrolledWindow could be created, adding the margin or padding as appropriate.