On 19/01/2021 08:53, Christopher Miles wrote:
> 
> For this problem, do you have any workable solution patch?

Maybe for a while it is better to avoid xdg-open or other handlers that 
launch actual viewers in background. E.g. to replace xdg-open with 
actual handlers in mailcap.

I attach a draft patch that just demonstrates my intention to use 
make-process. It intentionally does not use shell to run the command and 
such change could be breaking for some part of users. I have not tested 
if regexp substitutions for org-file-apps entries are not broken.

In kubuntu-18.04 I do not have any xdg-open entries in the system 
mailcap file. Even if I add such line to the user's file, I could not 
reproduce the problem with any of the real handler configured for the 
image/png type and launched by xdg-open: geeqie, gwenview, feh. I have 
no idea concerning the reason: older xdg-open version, other code 
working in xdg-open for kde desktop, or limited resources allocated to 
qemu virtual machine with ubuntu-20.04 where I can reproduce the problem.