This inheritance list is sorted roughly, but not completely, alphabetically:

Cfcn::ActionListener	Interface for listening to action events from widgets
Cfcn::ActivityBar	An activity bar widget that displays toggle buttons on the side of a window
Cfcn::DropDown	A dropdown list widget allowing single item selection from a list
Cfcn::MenuBar	A menu bar widget that displays menus at the top of a window
Cfcn::MenuPopup	A menu popup widget that displays a dropdown menu
Cfcn::TabbedArea	A container organizing content into selectable tabs
Cfcn::app_version	Static application version and metadata
Cfcn::Color	Color
Cfcn::ColumnLayout	Column layout specification passed to items for rendering
Cfcn::ContainerListener	Interface for listening to container modification events
Cfcn::DeathListener	Interface for listening to widget destruction events
Cfcn::GuiDeathListener	Internal listener that forwards death notifications from widgets to the owning Gui so it can clean up references
Cfcn::DragHandler	Manages drag and drop operations for a Gui instance
Cfcn::DragPayload	Container for arbitrary data carried during a drag operation
Cfcn::DragPoint	Simple 2D integer point used for drag offsets and positions
Cfcn::DragRenderConfig	Configuration for how drag visuals are rendered
Cfcn::DropTargetListener	Listener interface for widgets that accept dragged payloads
Cfcn::Event	Base class for all GUI event objects
Cfcn::ActionEvent	Represents an action trigger (e.g., button click)
Cfcn::ContainerEvent	Represents changes within a container (e.g., widget added/removed)
Cfcn::DragEvent	Drag and drop event type container
Cfcn::InputEvent	Base class for all input-related events (keyboard, mouse)
Cfcn::KeyEvent	Represents a key event
Cfcn::MouseEvent	Represents a mouse event
Cfcn::TextInputEvent	Text input event for IME (input method editor) composition, dead keys, and pasted text
Cfcn::SelectionEvent	Represents a change in selection state (e.g., list item selected)
Cfcn::float_traits< numT >	Generic template for floating-point type traits
Cfcn::float_traits< double >	Specialization of float traits for double
Cfcn::float_traits< float >	Specialization of float traits for float
Cfcn::FocusHandler	Manages focus navigation and assignment among widgets within a Gui instance
Cfcn::FocusHandler::ModalScope	Modal scope management (RAII guard)
Cfcn::FocusHandler::ModalState	Represents a single modal state level with focus and mouse owners
Cfcn::FocusListener	Interface for listening to focus gain/loss events
Cfcn::Button	A standard clickable button widget
Cfcn::ImageButton	An implementation of a regular clickable button
Cfcn::CheckBox	An implementation of a check box
Cfcn::RadioButton	An implementation of a radio button where a user can select or deselect the radio button and where the status of the radio button is displayed to the user
Cfcn::ToggleButton	An implementation of a toggleable button
Cfcn::ActivityBarItem	A toggle button item for use in an ActivityBar
Cfcn::MenuItem	A menu item widget for use in menus
Cfcn::DropDown	A dropdown list widget allowing single item selection from a list
Cfcn::MenuPopup	A menu popup widget that displays a dropdown menu
Cfcn::Font	Abstract interface for font rendering
Cfcn::DefaultFont	A basic font implementation capable only of drawing rectangles (placeholder)
Cfcn::ImageFont	A font implementation using an image atlas containing glyph data
Cfcn::sdl3::TrueTypeFont	SDL3/FreeType implementation for rendering TrueType fonts
Cfcn::font::FontLoader	Helper class for searching and loading fonts
Cfcn::Graphics	Abstract interface providing primitive drawing functions (lines, rectangles, etc.)
Cfcn::opengl::Graphics	OpenGL-specific implementation of the Graphics interface
Cfcn::sdl3::Graphics	SDL3 renderer-specific implementation of the Graphics interface
Cfcn::Gui	The central GUI manager
Cfcn::Image	Abstract holder for image data
Cfcn::opengl::Image	OpenGL-specific implementation of Image
Cfcn::sdl3::Image	SDL3-specific implementation of Image
Cfcn::ImageFontConfig	Configuration struct for ImageFont constructors
Cfcn::ImageLoader	Abstract interface for loading image assets
Cfcn::sdl3::ImageLoader	SDL3-specific implementation of ImageLoader
Cfcn::opengl::ImageLoader	OpenGL ImageLoader that loads images with SDL
Cfcn::Input	Abstract interface for polling user input devices
Cfcn::GenericInput	A generic input implementation usable with various backends
Cfcn::sdl3::Input	SDL3-specific implementation of Input
Cfcn::KeyInput	Internal class representing raw keyboard input data
Cfcn::KeyListener	Interface for listening to keyboard events
Cfcn::Button	A standard clickable button widget
Cfcn::DropDown	A dropdown list widget allowing single item selection from a list
Cfcn::ListBox	A scrollable list box allowing item selection
Cfcn::MenuBar	A menu bar widget that displays menus at the top of a window
Cfcn::MenuPopup	A menu popup widget that displays a dropdown menu
Cfcn::Slider	A control for selecting a numeric value by sliding along a scale
Cfcn::TabbedArea	A container organizing content into selectable tabs
Cfcn::TextBox	A multi-line text input field
Cfcn::TextField	A single-line text input field
Cfcn::PasswordField	Password input widget
Cfcn::ListModel	Interface for a data model representing a list (used by ListBox/DropDown)
Cfcn::Math< T >	Template utility providing math functions and constants for numeric type T
Cfcn::MenuColumns	Aggregated column metrics for all items in a menu
Cfcn::MenuItemMetrics	Layout metrics for a single menu item (content only, no padding/borders)
Cfcn::MouseInput	Internal class representing raw mouse input data
Cfcn::MouseListener	Interface for listening to mouse events
Cfcn::Button	A standard clickable button widget
Cfcn::DropDown	A dropdown list widget allowing single item selection from a list
Cfcn::ListBox	A scrollable list box allowing item selection
Cfcn::MenuBar	A menu bar widget that displays menus at the top of a window
Cfcn::MenuPopup	A menu popup widget that displays a dropdown menu
Cfcn::ModalBackdrop	A Transparent fullscreen backdrop
Cfcn::Panel	A Panel widget with a title bar and optional close button
Cfcn::PrimaryPanel	A primary (left-side) panel widget
Cfcn::SecondaryPanel	A secondary (right-side) panel widget
Cfcn::ScrollArea	A scrollable viewport for viewing widgets larger than the visible area
Cfcn::Slider	A control for selecting a numeric value by sliding along a scale
Cfcn::Tab	A single tab label used within a TabbedArea
Cfcn::TabbedArea	A container organizing content into selectable tabs
Cfcn::TextBox	A multi-line text input field
Cfcn::TextField	A single-line text input field
Cfcn::Window	A movable container window that can hold other widgets
Cfcn::PieGraph::PieGraphSegment	Represents a single segment of a pie graph (angles and color)
Cfcn::Point	Represents a 2D coordinate (X, Y)
Cfcn::Rectangle	Represents a rectangular area (X, Y, Width, Height)
Cfcn::ClipRectangle	A rectangle specifically used for clipping rendering regions
Cfcn::SelectionListener	Interface for listening to selection change events
Cfcn::DropDown	A dropdown list widget allowing single item selection from a list
Cfcn::semantic_version	Simple semantic version container
Cfcn::Shortcut	High-level shortcut binding a semantic key with a modifier mask
Cfcn::Size	Represents dimensions defined by width and height
Cfcn::Text	Helper class for text manipulation within widgets
Cfcn::TooltipModifierBehavior	Tooltip modifier behavior (for an ALT-key extended view)
Cfcn::TooltipSpec	Tooltip specification (data + behavior)
Cfcn::UTF8StringEditor	Utility for editing and handling UTF-8 encoded strings
Cfcn::Widget	Abstract base class defining the common behavior, properties, and lifecycle of all GUI elements
Cfcn::BarGraph	Displays data as a rectangular bar graph
Cfcn::Button	A standard clickable button widget
Cfcn::Container	A composite widget capable of holding and managing child widgets
Cfcn::ActivityBar	An activity bar widget that displays toggle buttons on the side of a window
Cfcn::AdjustingContainer	Self-adjusting Container class
Cfcn::BarSection	A container section for use within HorizontalBar or VerticalBar widgets
Cfcn::FlowContainer	An implementation of a flow container that can contain other widgets
Cfcn::HorizontalBar	A horizontal bar container that arranges children from left to right
Cfcn::MenuBar	A menu bar widget that displays menus at the top of a window
Cfcn::StatusBar	A status bar widget that displays information at the bottom of a window
Cfcn::MenuPopup	A menu popup widget that displays a dropdown menu
Cfcn::ModalBackdrop	A Transparent fullscreen backdrop
Cfcn::Panel	A Panel widget with a title bar and optional close button
Cfcn::Tab	A single tab label used within a TabbedArea
Cfcn::Tooltip	A tooltip widget
Cfcn::Window	A movable container window that can hold other widgets
Cfcn::CurveGraph	Displays data as a smooth curve based on a vector of points
Cfcn::DropDown	A dropdown list widget allowing single item selection from a list
Cfcn::Icon	Displays a static image icon
Cfcn::IconProgressBar	Displays progress using a sequence of icons
Cfcn::ImageProgressBar	Displays progress using images
Cfcn::Label	Displays a text caption
Cfcn::LineGraph	Displays data as a line graph connecting a vector of points
Cfcn::ListBox	A scrollable list box allowing item selection
Cfcn::PieGraph	Displays data as a circular pie chart
Cfcn::PointGraph	Draws a scatter graph of individual points
Cfcn::ScrollArea	A scrollable viewport for viewing widgets larger than the visible area
Cfcn::Slider	A control for selecting a numeric value by sliding along a scale
Cfcn::Spacer	Provides empty space to assist with layout management
Cfcn::TabbedArea	A container organizing content into selectable tabs
Cfcn::TextBox	A multi-line text input field
Cfcn::TextField	A single-line text input field
Cfcn::WidgetListener	Interface for receiving generic events from widgets
Cfcn::Button	A standard clickable button widget
Cfcn::VisibilityEventHandler	Handles changes in widget visibility states
Cstd::runtime_error
Cfcn::Exception	An exception class containing a message, a file, and a line number where the exception occurred