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

[detail level 1234]

LeechCraft::ActionInfo	Describes an action exposed in shortcut manager
Media::AlbumInfo	Information about an album used in IAlbumArtProvider
Media::AlbumRelease	Describes a recent release
LeechCraft::ANFieldData	A single additional AdvancedNotifications field
Media::ArtistBio	Information about artist biography
Media::ArtistInfo	A structure describing an artist
Media::AudioInfo	Describes a single audio track
Media::AudioSearchRequest	Describes a request for an audio search in an IAudioPile
LeechCraft::Util::DBLock	Provides database transaction lock
IEntityManager::DelegationResult
LeechCraft::Sync::Delta
LeechCraft::Entity	Describes parameters of an entity
EntityTestHandleResult	The result of testing whether the entity could be handled
Media::EventInfo	A structure describing an event like a gig or a festival
std::exception	STL class
LeechCraft::StandardException
LeechCraft::DependencyException
LeechCraft::InjectionFailureException
LeechCraft::ReleaseFailureException
LeechCraft::SerializationException
LeechCraft::UnknownVersionException
IDataFilter::FilterVariant
LeechCraft::FlatTreeItem
Media::HypedArtistInfo	Contains information about a hyped artist
Media::HypedTrackInfo	Contains information about a hyped track
IActionsExporter	Interface for embedding actions and menus into various places
IAdvancedHTMLEditor	Interface for HTML/WYSIWYG editors with some advanced functionality
Media::IAlbumArtProvider	Interface for plugins that can search for album art
IANEmitter	Interface for plugins emitting AdvancedNotifications entries
Media::IArtistBioFetcher	Interface for plugins supporting fetching artist biography
Media::IAudioPile	Interface for plugins supporting searching for tracks
Media::IAudioScrobbler	Interface for plugins that support scrobbling
IColorThemeManager
ICoreProxy	Proxy class for the communication with LeechCraft
ICoreTabWidget	This interface is used to represent LeechCraft's core tab widget
IDataFilter	Base interface for data filter plugins
Media::IDiscographyProvider	Interface for plugins supporting getting artist discography
IDNDTab
IDownload	Common interface for all the downloaders
LeechCraft::Util::IDPool< T >	A simple pool of identificators of the given type
LeechCraft::Util::IDPool< qint64 >
IEditorWidget	Interface to be implemented by editor widgets returned from ITextEditor::GetTextEditor()
IEntityHandler	Interface for plugins able to handle entities
IEntityManager	Proxy to core entity manager
Media::IEventsProvider	Interface for plugins that can provide events
IFinder	Base class for search providers
IFindProxy	Represents search results for a single Request
IHaveDiagInfo
IHaveRecoverableTabs	Interface for plugins that can recover tabs after restart
IHaveSettings	Interface for plugins that have user-configurable settings
IHaveShortcuts	Interface for plugins that support configuring shortcuts
IHaveTabs	Interface for plugins that have one or more tabs
LeechCraft::IHookProxy	Class for hook-based communication between plugins
LeechCraft::Util::DefaultHookProxy	Standard implementation of IHookProxy
Media::IHypesProvider	Interface for plugins that support fetching hypes
IImportExport	Interface for plugins which can import/export data to persistent storage
IInfo	Required interface for every plugin
IJobHolder	Interface for plugins holding jobs or persistent notifications
Media::ILyricsFinder	Interface for plugins supporting finding lyrics
IMediaPlayer
IMWProxy	This interface is used for manipulating the main window
Media::IPendingArtistBio	Pending biography request handle
Media::IPendingAudioSearch	Pending audio search handle
Media::IPendingDisco	Pending discography request handle
Media::IPendingSimilarArtists	Pending similar artists request handle
Media::IPendingTagsFetch	Pending tags fetch handle
IPlugin2	Base class for second-level plugins
IPluginAdaptor	This class is used to provide plugins for LeechCraft from additional sources
IPluginReady	Base class for plugins accepting second-level plugins
IPluginsManager	This interface is used to represent LeechCraft's global plugin manager
IQuarkComponentProvider	Interface for plugins providing quark components
Media::IRadioStation	Describes a single radio station
Media::IRadioStationProvider	Interface for plugins providing radio stations
Media::IRecentReleases	Interface for plugins providing recent releases
Media::IRecommendedArtists	Interface for plugins supporting recommended artists
IRecoverableTab	Interface for a single tab that may be recovered
IRemovableDevManager
IRootWindowsManager	Interface to the core windows manager
IScript	Interface for objects representing scripts
IScriptLoader	Interface for plugins providing scripting
IScriptLoaderInstance	Interface for script loaders
IShortcutProxy	Proxy for requesting shortcuts from the shortcut manager in the Core
Media::ISimilarArtists	Interface for plugins supporting similar artists
IStartupWizard	Interface for adding page to the common startup wizard
ISummaryRepresentation
ISyncable	Interface for plugins that have content/data/settings that can be synchronized via other plugins — syncers
ITabWidget	This interface defines methods that should be implemented in widgets added to the main tab widget
ITaggableJobs	Interface for plugins having taggable download jobs
Media::ITagsFetcher	Interface for plugins fetching tags for untagged files
ITagsManager	Tags manager's interface
ITextEditor	Interface for plugins implementing a text editor component
IVideoWidget
IWebBrowser	Base class for plugins that provide a web browser
IWebFileStorage
IWebWidget	Common interface for a web widget
LeechCraft::Util::ListModelItem
Media::LyricsQuery	Describes a lyrics search request
LeechCraft::Sync::Payload
QAbstractItemModel
LeechCraft::Util::FlattenFilterModel
LeechCraft::Util::FlatToFoldersProxyModel
LeechCraft::Util::ListModel
LeechCraft::Util::MergeModel
QCompleter
LeechCraft::Util::TagsCompleter	Completer suitable for tag completion
QDeclarativeImageProvider
LeechCraft::Util::WidthIconProvider	Provides scalable icons to QML
LeechCraft::Util::ThemeImageProvider	Provides icons from the current theme by their FDO name
QDeclarativeView
LeechCraft::Util::UnhideListViewBase
QFile
LeechCraft::Util::FileRemoveGuard	QFile removing itself from file system on destruction
QLayout
LeechCraft::Util::FlowLayout	A simple flow layout implementation
QLineEdit
LeechCraft::Util::TagsLineEdit	A line edit class suitable for use with TagsCompleter
QNetworkCookieJar
LeechCraft::Util::CustomCookieJar	A customized cookie jar with additional features
QNetworkReply
LeechCraft::Util::CustomNetworkReply	A network reply with customizable content and reply headers
QObject
LeechCraft::Util::AutoResizeMixin
LeechCraft::Util::BaseHookInterconnector	Base class for signal-slot relays in plugin APIs
LeechCraft::Util::ClearLineEditAddon	Provides a "clear text" action for line edits
LeechCraft::Util::ColorThemeProxy	Proxy for QML files to use colors from current color theme
LeechCraft::Util::NotificationActionHandler	Aids in adding actions to notifications
LeechCraft::Util::QueueManager	A simple scheduling manager for a queue of functors
LeechCraft::Util::ResourceLoader	Utility class for loading a file from a set of locations
LeechCraft::Util::ShortcutManager	Aids in providing configurable shortcuts
LeechCraft::Util::StdDataFilterMenuCreator
LeechCraft::Util::SyncDeltaManager
LeechCraft::Util::UnhoverDeleteMixin	Allows to hide a widget or popup after mouse leave
QSortFilterProxyModel
LeechCraft::Util::TagsFilterModel	Provides filter model with additional tags filter mode
QStandardItemModel
LeechCraft::Util::UnhideListModel
QStringListModel
LeechCraft::Util::TagsCompletionModel	A QStringListModel providing additional methods for tags
QTreeWidget
LeechCraft::Util::CategorySelector	Way to select amongst a group of items
LeechCraft::QuarkComponent	Describes a single quark
QWidget
LeechCraft::Util::BackendSelector	A common dialog to select storage backend
LeechCraft::Util::PageNotification
LeechCraft::Util::FindNotification	A horizontal bar with typical widgets for text search
LeechCraft::Util::SelectableBrowser	A "browser" that shows HTML either via QTextBrowser or a browser plugin
Media::ReleaseInfo	Information about a release, like an album or a single
Media::ReleaseTrackInfo	Information about a track release
LeechCraft::Request	Describes the elementary subrequest
Media::IPendingAudioSearch::Result	A structure describing a single entry in search result
Media::SimilarityInfo	Describes similarty information of an artist
LeechCraft::Util::VersionActionMapper< ActionType, VerType >::Simple
LeechCraft::TabClassInfo	The structure describing a single tab class
LeechCraft::TabRecoverInfo	Keeps the tab state between runs
Media::TagInfo	Information about a tag like a genre
LeechCraft::Util::TreeItem
LeechCraft::Util::ValueFinder< T >
LeechCraft::Util::VersionActionMapper< ActionType, VerType >