FreeType is a font rasterization
library used by matplotlib which supports TrueType, Type 1, and
OpenType fonts.
GTK
The GIMP Toolkit (GTK) graphical user interface
library
PyGObject
PyGObject provides Python wrappers for the
GTK widgets library
pyqt
pyqt provides python
wrappers for the Qt widgets library and is required by
the matplotlib Qt5Agg and Qt4Agg backends. Widely used on linux
and windows; many linux distributions package this as
'python-qt5' or 'python-qt4'.
Qt
Qt is a cross-platform
application framework for desktop and embedded development.
Qt4
Qt4 is the previous,
but most widely used, version of Qt cross-platform application
framework for desktop and embedded development.
Qt5
Qt5 is the current
version of Qt cross-platform application
framework for desktop and embedded development.
Tk
Tk is a graphical user interface for Tcl
and many other dynamic languages. It can produce rich, native
applications that run unchanged across Windows, Mac OS X, Linux
and more.
wxpython
wxpython provides python wrappers
for the wxWidgets library for use with the WX and WXAgg
backends. Widely used on linux, OS-X and windows, it is often
packaged by linux distributions as 'python-wxgtk'
wxWidgets
WX is cross-platform GUI and
tools library for GTK, MS Windows, and MacOS. It uses native
widgets for each operating system, so applications will have the
look-and-feel that users on that operating system expect.