Eli Zaretskii wrote:
> Please rebase on master (Emacs 26), as it's too late for the release
> branch.

I have adapted Fabrice patches (attached) to master and with it I have 
built Emacs master last night (r128068.55b5265) on MSYS2/MINGW64 (with 
the PKGBUILD for mingw-w64-emacs-git). I do not know if I did all OK and 
have not tested every thing.

For example, now when I visit a PNG buffer, it fits window width by 
default. If I do (on menu bar) Image - Fit to Window Height, it fits but 
there is a BELL sound and this message on minibuffer:

Assertion failed: (= (cdr size) (- (nth 3 (window-inside-pixel-edges)) 
(nth 1 (window-inside-pixel-edges)))), 821, 814
user-error: Minibuffer window is not active

I tried with a few JPG files and they didn't display. In the minibuffer:

Cannot display image: ((= (cdr size) (- (nth 3 
(window-inside-pixel-edges)) (nth 1 (window-inside-pixel-edges)))) 821 814)

After a while I retried with the same PNG file (which before was 
displayed) but now it was not. Same "Cannot display..."



I wonder if this is to be expected or if it is a consequence of the 
patches...

Ciao,
  Angelo.