The biggest problem is that some changes in configuration files, related to sensitive packages like grub, systemd…, can break the whole system, so this popup window should appear at the end of upgrades to tackle any urgent modification before the user attempt any reboot.
Running it as background service with interval checks can fail to trigger the detection if the user directly reboots the system after all upgrades are finished.
This is a good point… Maybe I can work around this by creating a pacman hook which creates a pilot file when pacman creates pac* files. Systemd path will take care of monitoring this file and if it sees it modified, launch the GUI program (always at user level). Note that all the effort is not to redesign pacdiff but to have a minimal GUI that mimics its features.
Here’s just a stupid idea… What about a notifier icon in the system tray that, when clicked, brings up the application via pkexec? Because actually merging the .pacnews is going to require superuser privileges anyway. 
Well manjaro-pacnew-checker is at version 0.3.1. Now checking is in real time via a ALPM hook + systemd
I’ll install, use, and give feedback later.
What about the safeguard idea? As I explained, there are .pacnew files you don’t want the “normal user” (also called the noobs, or worse) to mess with, without at least warnings or something else that will prevent them to break the system. Especially if you had the idea to add this tool to other Majaro main tools, many user will destroy their system (it may be better they don’t touch .pacnew file rather than destroying critical system file by replacing with .pacnew).
I agree, simple way Is to add a disclaimer with the link for ask on the forum what Is best to do with the pac* showed and in the meantime i change also the default choice to “nothing to do”
Safeguard would be to have a warning in post #1 of release announcements:
so the warning is also visible in announcements by email, RSS and social network feeds
So nobody who needs to see it would see it. The people who need to see that don’t go to the forum let alone read the announcement threads.
And that is most likely already the case, important config changes are usually announced.
There was no warning about /etc/pacman.conf.pacnew in post #1 of Stable update 2023-07-10
And even people with reading abilities seem to have overlooked information posted by @cscs in post #2 about merging /etc/pacman.conf.pacnew.
Many more posts than usual from new users and ‘been a while since…’ users
No surprise considering it has been a while since users on stable branch had to deal with a .pacnew file
And that’s adding to my point. Having the info in the forum is useless anyway for these non technical people, the safeguard with this tool should not be a message in the forum but something in the tool itself.
And about this pacman.conf file it is not what I call a critical system file, replacing it with the pacnew is completely OK.
Now replace shadow.conf with its .pacnew and see the result 
Which posits a very serious question regarding what demographic Manjaro is for.
As I see it, Manjaro, by virtue of being Arch-based, is a distribution for people willing to assume the responsibility of maintaining it as it should. It is not — and, again, by virtue of its origins as an Arch spin-off, cannot be — a household kitchen sink appliance for consumers. They would be better off using a distribution designed to be used that way — something like Ubuntu.
The user cannot have it both ways, and as the supporting community, neither can we. Either we stay true to ourselves and to the nature of Manjaro, or we turn it into yet another clone of Ubuntu, Mint, or whatever else is out there.
There are already plenty of people out there who install Manjaro and then don’t update their system in years. And for that matter, do we really want to turn Manjaro into a distro for hardcore gamers at the expense of the community of helpful volunteers and the quality of the distribution?
Who knows what lurks in shadow.conf.pacnews?
The Shadow knows…
…I’ll see myself out…
I agree a lot of people using Manjaro shouldn’t use Manjaro. But what do we do now? Do as you see fit regarding this tool in the end, I’m just giving feedback/advice based on the reality of the demographic. This tool is great, but for these people it is a straight path to destruction with some of the .pacnew files they will overwrite/merge without the proper knowledge.
PS: also I don’t know what you mean regarding “gaming” this is kinda off topic.
It was a reference to the demographic that Manjaro appears to attract, whether intentional or not.
I know, right?
Obviously use Arch and stop messing around. 
TELL US THAT THEN.
Tell everybody that doesn’t fit your view of “people belonging to YOUR community” to uninstall!!!
I read this as the official stance from Manjaro, and the community should know that.
The rules in the forum should be changed, you HAVE to belong here and talking down on people is ok if you have a neck beard,
From manjaro.org AGAIN:
It is user-friendly and suitable for those new to computers, and can be installed on a wide range of devices.
Hypocrites.
I’m not a hypocrite. As a Arch based distro, Manjaro needs the user to have technical knowledge and willing to learn. Fact number one. That’s just a fact, and we can see MANY people in the community not willing to learn and lacking the most basic knowledge when it comes to issues, fact number two… That’s all. Now you want to make a scene out of it, please yourself.
I was just commenting about the topic and the reality, this tool may create more issues than helping people if not properly safeguarded.
Whoah, there friend. I was joking around.