>> We'd need a variable, say ‘window-inhibit-configuration-change-hook’.
 >
 > inhibit-window-configuration-change-hook ?

We can abuse ‘frame-after-make-frame’.  Try the attached, completely
untested patch.

BTW I just noticed that we still run ‘window-configuration-change-hook’
in far too many cases.  I'll have to remove it from ‘window-resize’,
‘window--resize-mini-window’, ‘adjust-window-trailing-edge’ and
‘balance-windows’.

 > The problem is, that it does work when edebugging it.  Anyway, I think I've
 > found the problem: It's the call to set-window-start, which in my
 > understanding forces the next redraw to scroll the window, thus
 > negating image-modes work.

Would my patch work around that?

martin