It is for Unix based systems running X11 and using GTK (the Gimp ToolKit). Gnotepad+ was designed to have as little bloat as possible, while still providing many of the common features found in a modern GUI-based text editor. It is still fairly light-weight, especially for the features it offers, and aims to remain that way. If you are looking for a programmers' editor, look for another text editor or help improve the GTK Text Widget.
