This page is about building tomboy-ng from source and contributing to its developement. You do not need to do any of this to just use tomboy-ng, a key feature is its absolute minimal requirements at install time.
Tomboy-ng is built using -
Free Pascal Compiler - https://freepascal.org/
Lazarus - https://www.lazarus-ide.org/
KControls - http://www.tkweb.eu/en/delphicomp/kcontrols.html
Pascal as a computer language is quite old, in the early days of the PC it went toe to toe with C and lost. But it still has quite a following and current estimates place it in the top twenty languages (source ?). Today, Object Pascal is a very functional object orientated language that drives Delphi and its cross platform open source rival, Lazarus.
Pascal is still widely used as a teaching language, its strong typing promotes good programming habits and allows the compiler to pick up many common errors. Lazarus provides an easy to use IDE where a programmer can drag components onto a form and then attach code to the component's events.
You are strongly encouraged to try building tomboy-ng for yourself. On the download page is a source code kit that you could use to build your binary. You would first need to install Free Pascal, Lazarus and the KControls component. You may choose to get the first two from your normal distro source if they offer Lazarus 1.6.4 or later but I strongly recommend direct from -
https://sourceforge.net/projects/lazarus/files/ choose your OS and then Lazarus 1.8, you will see debs, rpms, dmg files and windows kits for the compiler (FPC) and, separately, the FPC-src, and finally the IDE, Lazarus. To learn more see Free Pascal and Lazarus websites. Both have very active forums and extensive (but incomplete) wiki's.
Note on the Mac, installing FPC, FPC-src and Lazarus is a bit more involved, see Installing Lazarus on MacOS X unless you have done this before.
Next, get KControls. https://bitbucket.org/tkweb/kcontrols/downloads/ download the zip file, unzip somewhere suitable and install in Lazarus.
To learn more about KControls, see KControls Notes page.
You will find the source for tomboy-ng at the Github repo
Note that there is a Lazbuild command but its probably easier for first time users to compile from within the IDE. In fact you do need to start up the IDE and confirm some default settings before doing anything else.
The source tarball includes two scripts I use to build release packages. Both are driven from the command line and produce ready to ship packages. The Mac one, which makes dmg files depends on an external dmg building script, details in the script. The second script builds both Linux and Windows packages, 32bit and 64bit. In runs on a linux box that has a full lazarus install AND the additional libraries needed to build the Windows kits. As such, a suitable environment is a bit complicated but certainly not difficult.