Here is a list of all documented files with brief descriptions:

[detail level 12345]

lib
api
gumball
core
gumball_backend.h	Abstract backend functions
gumball_logger.h	Gumball logger
gumball_manager.h	GUM_Manager is a resource manager for libGumball
elements
gumball_button.h	GUM_Button data structure and hierarchy graph
gumball_common.h	Gumball_common is a collection of macros that are common to all elements in libGumball
gumball_container.h	GUM_Container data structure and hierarchy graph
gumball_controller.h	GUM_Controller data structure and hierarchy graph
gumball_root.h	GUM_Root data structure and hierarchy graph
gumball_widget.h	GUM_Widget data structure and hierarchy graph
ifaces
gumball_iresource.h	GUM_IResource data structure and hierarchy graph
types
gumball_color.h	GUM_Color is a simple RGBA color structure
gumball_event.h	GUM_Event is the base event type used in libGumball
gumball_font.h	GUM_Font data structure and hierarchy graph
gumball_rectangle.h	GUM_Rectangle is a simple rectangle structure
gumball_renderer.h	GUM_Renderer is the renderer type used in libGumball It exists for backends that require one, such as SDL
gumball_texture.h	GUM_Texture data structure and hierarchy graph
gumball_vector2.h	GUM_Vector2 is a simple 2D vector structure
gumball.h	Global include file for entire library
gumball_core.h	Core module-wide include
gumball_elements.h	Elements module-wide include
gumball_ifaces.h	Interfaces module-wide include
gumball_types.h	Types module-wide include