OpenToonz - OpenToonz is an animation program that is a free software version of Toonz, the animation software...
wxWidgets - wxWidgets: Cross-Platform GUI Library
Adobe Animate - Adobe Animate is a Flash, vector animation software.
Electron - Build cross platform desktop apps with web technologies
Pencil2D - Pencil2D is an opensource animation/drawing software for Mac OS X, Windows, and Linux, based on old...
GTK - GTK+ is a multi-platform toolkit for creating graphical user interfaces.