manual tiling window manager for X11

herbstluftwm

manual tiling window manager for X11

In herbstluftwm the layout is based on splitting frames into subframes which can be split again or can be filled with windows, Tags (or workspaces or virtual desktops or ...) can be added/removed at runtime. Each tag contains an own layout and exactly one tag is viewed on each monitor. The tags are monitor independent.
office productivity suite -- spreadsheet

libreoffice-calc

office productivity suite -- spreadsheet

LibreOffice is a full-featured office productivity suite that provides a near drop-in replacement for Microsoft(R) Office.
tabbed document viewer

qpdfview

tabbed document viewer

qpdfview is a simple tabbed document viewer which uses the Poppler library for PDF rendering and CUPS for printing and provides a clear and simple Qt graphical user interface. Support for the DjVu and PostScript formats can be added via plugins.
following DIAGNOSTICS in man page

systemd-cron

systemd generator that provides cron daemon & anacron functionality

This is a generator that dynamicaly translates /etc/crontab, /etc/cron.{d|hourly|daily|weekly|monthly|yearly}/* and user cronjobs into systemd .timer & .service units.
mail/news client with RSS, chat and integrated spam filter support

thunderbird

mail/news client with RSS, chat and integrated spam filter support

Thunderbird is an mail client suitable for free distribution. The goal of Thunderbird is to produce a cross platform stand-alone mail application using the XUL user interface language. It supports different mail accounts, no matter of the used protocol like POP(s) or IMAP(s), has an integrated learning Spam filter, and offers easy organization of mails with tagging and virtual folders. Also, more features can be added by installing extensions.
Plasma extension that monitors the current status of gamemode

plasma-gamemode

Plasma extension that monitors the current status of gamemode

GameMode optimises your system for peak performance when running a game.