As you may know, Notepadqq is an open-source clone of Notepad++, written in QT. Among other features of Notepadqq, its worth writing about its syntax highlighing for the most popular programming languages, search-find-replace through regular expressions, split-screen, bookmarks, code folding, et cetera.
The latest version available is Notepadqq 0.51, which has been recently released, bringing a few changes only.
For Ubuntu 16.04 Xenial Xerus, Ubuntu 15.10 Wily Werewolf, Ubuntu 14.04 Trusty Tahr and derivative systems like Linux Mint 17.x, Elementary OS 0.3 Freya, the latest notepadqq builds are available via some third party PPA, so installing the software should not be to difficult.
Just add the PPA to your system, update the local repository index and install the notepadqq package:
$ sudo add-apt-repository ppa:notepadqq-team/notepadqq
$ sudo apt-get update
$ sudo apt-get install notepadqq
Optional, to remove notepadqq, do:
$ sudo apt-get remove notepadqq
For Arch Linux, Manjaro and other Arch-based notepadqq is available the AUR repository, so it can be easily installed via yaourt:
$ sudo pacman -Sy yaourt
$ sudo yaourt notepadqq
Optional, to remove Notepadqq on Arch Linux, Manjaro and derivative systems, do:
$ sudo yaourt -Rsn notepadqq