I've stumbled upon this site: https://sites.google.com/site/easylinuxtipsproject/ and I have to say, I don't really understand many of those tips. The "Don't mix desktop environments" is one of them.
The author of the site says:
(direct source of the quotation)Don't mix desktop environments: stick to the default
6. An Ubuntu or a Linux Mint in which you install the full KDE desktop alongside the existing other desktop environment (Mate, Cinnamon, Unity, Xfce, Gnome), becomes a hopelessly polluted mess. This pollution will decrease performance and may cause instability and malfunctions.
If you want to ensure that your operating system continues to work well, stick to the default desktop environment. And don't install any KDE applications in Ubuntu or Linux Mint, that upon installation pull in half of the KDE desktop as dependent files (like for example DVD burner K3B does)...
Tip: when you install applications by means of Synaptic Package Manager, then you can check beforehand what a particular application needs as dependent files.
Desktop environments that share a lot "under the hood", you may install alongside each other, if you wish. For example: Xfce (the desktop environment of Xubuntu) fits pretty nicely alongside the Gnome/Unity of Ubuntu and the Cinnamon/Mate of Linux Mint. But even then some pollution is inevitable...
Have you made this mistake and do you wish to undo it? Then the best approach is unfortunately a clean re-installation.
IIUC, a DE, like any other (complex) program, is effectively a bunch of executables, shared libraries, and config files. Therefore (perhaps out of my ignorance), I do not see why can't e.g. Cinnamon and KDE coexist together.
Let's say the user has installed both of them on one system. If he chooses to run Cinnamon, then Cinnamon's executables, shared libraries and config files are loaded to the memory; if, however, the user chooses to run KDE, then KDE's files are loaded. Since Cinnamon is GNOME-based, and GNOME and KDE are sth like two different ecosystems, then I do not see how could Cinnamon and KDE go into conflict, if they are not run both at the same time, just because of how different they are! How can a program damage the system by simply existing, if it's not run?
What I could understand is why I shouldn't run any KDE application inside any non-KDE environment; well, doing so would result in KDE's libraries (used by that application) and e.g. Cinnamon's libraries (Cinnamon's running at the moment, duh) loaded at the same time, to maybe some conflict could arise... I do not have much experience, and I actually never tried to mix two different DE's, yet I did try two times to install Kate in a GNOME system - Ubuntu for the first time, Fedora for the second. And I experienced no problems because of this (although I did eventually screw up Fedora... IIUC the direct reason of Fedora's malfunction was different, however). Also, from practical point of view, it would really be nice to be able to install KDE's software into a Cinnamon Mint; while one may, e.g, like Cinnamon, he might also prefer Kate over gedit...
Also, I do not understand why the only option to undo the installation of another desktop enviromnent is a clean reainstallation of the whole system. Quoting the Official User Guide for Linux Mint 17 Cinnamon Edition:
. So, if I install KDE through the Software Manager, I should be able to revert the system to the state before this installation any moment, shouldn't I?Because the package management software keeps a complete record of all of its actions, it is quite capable of reversing any steps that it took in the past, while ensuring that removing one package will not cause any other package to fail.
Last but not least - the User Guide seems to encourage users to mix desktop environments! Let me quote it:
Well, I was about to try installing KDE or LXDE nearby Cinnamon, just out of curiosity - but now I got a little bit scared... Anyway, I'll be gratefull if anyone wishes to clarify these topics.There's a lot more to learn about Linux Mint and about Linux in general. This guide was just an overview of some of the aspects related to your desktop. By now you should feel more comfortable with using it and you should have a better understanding of some of its components. Where are you going to go next? Will you learn how to use the terminal? Will you give other desktops a try (KDE, XFCE, etc.)? It's entirely up to you. Remember, Linux is about fun and the community is there to help. Take your time and learn a little bit every day. There's always something new no matter how much you know already.