KDE
Installation
Install the kde5 package, and optionally, the kde5-baseapps package.
To use the "Networks" widget, enable the dbus and NetworkManager services.
Installing the kde5 package also installs the sddm package, which provides
the sddm service for the Simple Desktop Display Manager. This service depends
on the dbus service being enabled; test the
service before enabling it. If you are
not intending to run SDDM via a remote X server, you will need to install either
the xorg-minimal package or the xorg package. By default, SDDM will start an
X-based Plasma session, but you can request a Wayland-based Plasma session
instead.
If you wish to start an X-based session from the console, use
startx to run startplasma-x11. For a Wayland-based
session, run startplasma-wayland directly.
Dolphin
Dolphin is the default file manager of the KDE desktop environment. It can be
installed on its own by installing the dolphin package, or it can be installed
as part of the kde5-baseapps meta-package.
Thumbnail Previews
To enable thumbnail file previews, install the kdegraphics-thumbnailers
package. If you want video thumbnails, the ffmpegthumbs package is also
necessary. Enable previews in "Control" -> "Configure Dolphin" -> "General" ->
"Previews" by checking the corresponding boxes. File previews will be shown for
the selected file types after clicking "Preview" in Dolphin's toolbar.