ZTree colours source code in View the way Notepad++ does, from Notepad++'s
own language and style definitions:

  langs.model.xml    the languages: their file extensions, comments and
                     keyword lists
  stylers.model.xml  the colours (Notepad++'s default theme)

Both files are part of Notepad++ v8.9.8.1, unchanged:
  https://notepad-plus-plus.org
  https://github.com/notepad-plus-plus/notepad-plus-plus  (PowerEditor/src)

Notepad++ is Copyright (C) Don HO and its contributors, and is distributed
under the GNU General Public License, version 3 or later. Its licence,
including the full GPL text, is in LICENSE.notepad++.txt next to this file.
ZTree itself is not covered by that licence: it reads these files as data.

Using your own settings or another theme: put a langs.xml and/or a
stylers.xml in this folder; they are used instead of the .model.xml files.
For dark colours, copy Notepad++'s themes/DarkModeDefault.xml (or any other
theme) here under the name stylers.xml.
