Credits to
Denis Auroux: „Xournal“ for inspiration
http://xournal.sourceforge.net/
Michael Zimmermann: SVG drawing of set square
http://commons.wikimedia.org/wiki/File:Set_square_Geodreieck.svg
blackboard logo from Nuvola icon theme
https://www.iconfinder.com/iconsets/nuvola2
Thanks to
the JAVA community, especially „stack overflow“
http://stackoverflow.com/questions/tagged/java
the authors of „Geany“
http://geany.org