I’d like to play a bit with Themes and the sorts,
i saw that it would be preferable for system stability to apply; style,colors,fonts,icons,cursors etc. separately,instead of setting a Global theme.
i intend on getting those directly from the KDE’s ‘system setting’(Get new…).
i was wondering if it’s safe security wise(malwares and stuff)and also if it can cause a slower GUI or other weird bugs.?
Install timeshift, put the snapshots on a safe space, e.g. external disk, make sure to have a Manjaro ISO on a live stick available - then you can play around at bit and will be able to restore your system if it breaks.
It’s probably riskier to tinker on its own with the various theme components than to directly install a global theme.
Although the suggestions you already received are error-proof and a really good practice, they may be a little bit overkill in this case, you can go quite serene when tinkering with themes, especially if they come from the “Get new…” source of Plasma. Of course better safe than sorry.
Now, Global Themes do in fact carry some Javascript code with them, which is used to setup all the panels layouts as the theme maintainer wanted to ship. I’ve no big experience when it comes to web-related languages like JS, but I think that this may be a “vector of attack”: if you want to be sure always check the zip/tar file from the pling/opendesktop website (all the packages coming from the “get new X…” section are hosted there). The code is open of course, so you can take a glance and see if there’s some suspicious activity.
On the other hand, IIRC, theme components like colorschemes etc do not come with JS or other interpreted code.
As a rule of thumb always check what you are downloading.
Source: I’m a KDE third-party theme maintainer myself
Installing themes for the most part is not risky nor will it hurt your system. Read the notes on the KDE Store theme you want to use before you jump, otherwise, jump. The advice further upthread on backups and keeping a good live-usb are priceless. DO IT. Even if all you are doing is downloading and running Manjaro updates. Keep a good set of backups in whatever way makes the most sense to you.
If you’ve never had to reproduce from a backup you might not understand. If you’ve ever lost your system and either had/not had a good backup to restore, you do understand.