Here are the classes, structs, unions and interfaces with brief descriptions:

[detail level 12345]

VST3Editor
KeyboardHook
VST3EditorInternal
VSTGUI
Animation
AlphaValueAnimation	Animates the alpha value of the view
ViewSizeAnimation	Animates the view size of the view
ExchangeViewAnimation	Exchange a view by another view with an animation
ControlValueAnimation	Animates the value of a CControl
Animator	Animation runner
FinishedMessage	Animation Finished Message Object
IAnimationTarget	Animation target interface
ITimingFunction	Animation timing function interface
TimingFunctionBase
LinearTimingFunction
PowerTimingFunction
InterpolationTimingFunction
CubicBezierTimingFunction
RepeatTimingFunction
BitmapFilter
Standard	Standard Bitmap Filter Names
Property	Standard Bitmap Property Names
Property	Filter Property
IFilter	Filter Interface
Factory	Bitmap Filter Factory
FilterBase	A Base Class for Implementing Bitmap Filters
Call
CClipboardDetail
StringDataPackage
CDrawMethods
Constants
Detail
EventPrivate
ExternalView
IntPoint
IntSize
IntRect
IView	Interface for embedding views from external view systems
IControlViewExtension
EditCallbacks
IViewEmbedder	Interface for view embedder classes
ViewAdapter	Adapter for the IView interface
ControlViewAdapter
PixelBuffer
Private
Standalone	Standalone Library
Application
ConfigValue	Configuration Value
Init	Init application
DelegateAdapter	Application delegate adapter
Info	Application info
IDelegate	Application delegate interface
Async	asynchronous tasks
Group	Group of asynchronous tasks
CommandGroup	Predefined command groups
CommandName
Commands	Predefined commands
Debug
UIDesc
CustomizationAdapter	ICustomization adapter
Customization	Customization helper for an UIDesc window
ValueCalls
ModelBindingCallbacks
IModelBinding	Model binding interface
ICustomization	UIDesc window customization interface
Config	Configuration for an UIDescription window
Value	value create and helper functions
Detail
ListenerBase
ListenerT	Value listener
Listener	Value listener
MenuBuilderAdapter	Menu builder adapter
NoMenuBuilder	No menu builder adapter
Preferences
IStringListValue
IMutableStepValue
IRangeValueConverter
IStringValue
ValueListenerAdapter	Value listener adapter
WindowControllerAdapter	Window controller adapter
WindowListenerAdapter	Window listener adapter
WindowClosedListener	Window closed listener
AlertBoxConfig	Alertbox configuration
AlertBoxForWindowConfig	Alertbox for window configuration
IApplication	Application interface
Command	Command definition
ICommandHandler	Handler for commands
ICommonDirectories
IMenuBuilder	Menu builder interface
IPreference	Preference interface
ISharedUIResources	Shared UI resources interface
IValue	Value interface
IStepValue	Extension to IValue for a non continous value with discrete steps
IValueConverter	Value converter interface
IValueListener	Value listener interface
WindowStyle	Window style
WindowConfiguration	Window configuration
IWindow	Window interface
IWindowController	Window controller interface
IWindowListener	Window listener interface
String
UIDescriptionPrivate
StringToken
UIViewCreator
AnimationSplashScreenCreator
AnimKnobCreator
AutoAnimationCreator
CheckBoxCreator
CControlCreatorDummyControl
ControlCreator
GradientViewCreator
KickButtonCreator
KnobBaseCreator
KnobCreator
LayeredViewContainerCreator
MovieBitmapCreator
MovieButtonCreator
IMultiBitmapControlCreator
MultiBitmapControlCreator
MultiLineTextLabelCreator
OnOffButtonCreator
OptionMenuCreator
ParamDisplayCreator
RockerSwitchCreator
RowColumnViewCreator
ScrollViewCreator
SearchTextEditCreator
SegmentButtonCreator
ShadowViewContainerCreator
SliderBaseCreator
SliderCreator
SplitViewCreator
StringListControlCreator
SwitchBaseCreator
VerticalSwitchCreator
HorizontalSwitchCreator
TextButtonCreator
TextEditCreator
TextLabelCreator
UIViewSwitchContainerCreator
ViewContainerCreator
ViewCreator
VuMeterCreator
XYPadCreator
VST3EditorInternal
Xml
IHandler
Parser
CBitmap	Encapsulates various platform depended kinds of bitmaps
CMultiFrameBitmapDescription	Description for a multi frame bitmap
CMultiFrameBitmap	Multi frame bitmap
MultiFrameBitmapView	Injection class for views that draw frames of a CMultiFrameBitmap
CNinePartTiledDescription
CNinePartTiledBitmap	Nine-part tiled bitmap
CBitmapPixelAccess	Direct pixel access to a CBitmap
CButtonState	Button and Modifier state
CClipboard
CColor	RGBA Color structure
CDataBrowser	DataBrowser view
Cell	CDataBrowser Cell position description
CDrawContext	A drawing context encapsulates the drawing context of the underlying OS
Impl
State
Transform	Add a transform to all draw routines
ConcatClip
CDrawMode
CDropSource	Drop source
CExternalViewBaseImpl
CExternalView	View to embed non CView views into VSTGUI
Impl
CExternalControl
Impl
CFileExtension	File extension description
Impl
CNewFileSelector	New file selector class
Impl
GlobalFonts
CFontDesc	Font class
ModalViewSession
CFrame	The CFrame is the parent container of all views
CollectInvalidRects
Impl
PostEventHandler
VSTGUIEditorInterface
IMouseObserver	Generic mouse observer interface for CFrame
OldMouseObserverAdapter
IKeyboardHook	Generic keyboard hook interface for CFrame
OldKeyboardHookAdapter
IViewAddedRemovedObserver	View added removed observer interface for CFrame
IFocusViewObserver	Focus view observer interface for CFrame
CGradient	Gradient Object [new in 4.0]
CGradientView	View which draws a gradient
CGraphicsPath	Graphics Path Object
CGraphicsTransform	Graphics Transform Matrix
CInvalidRectList
CLayeredViewContainer	View container which draws into a platform layer on top of a parent layer or the platform viewA CLayeredViewContainer creates a platform layer on top of a parent layer or the platform view of CFrame if available on that platform and draws into it, otherwise it acts exactly like a CViewContainer
CLineStyle
COffscreenContext	A draw context using a bitmap as it's back buffer
CAutoAnimation
COnOffButton	Button control with 2 states
CCheckBox	Check box control with a title and 3 states
CKickButton
CTextButton	Button which renders without bitmaps
IColorChooserDelegate
CColorChooserUISettings
CColorChooser
CControl	Base class of all VSTGUI controls
Impl
IMultiBitmapControl	Interface for controls with sub images
CMouseWheelEditingSupport	Helper class for mouse wheel editing
IFontChooserDelegate
CFontChooserUIDefinition
CFontChooser
CKnobBase
MouseEditingState
CKnob	Knob control
CAnimKnob	Bitmap knob control
CListControl	Control which draws a list of configurable rows
Impl
CListControlRowDesc	The description of one row for the CListControl
IListControlDrawer	The list control drawer interface
Row
IListControlConfigurator	The list control configurator interface
StaticListControlConfigurator	A list control configurator implementation
CMovieBitmap	Bitmap view that displays different bitmaps according to its current value
CMovieButton	Bi-states button with 2 subbitmaps
CMenuItem	Menu item
Impl
CCommandMenuItem	Command menu item
Desc
COptionMenu	Popup menu control
CParamDisplay	Parameter display
CScrollbar	Scrollbar control
IScrollbarDrawer
CSearchTextEdit	Search text edit field
CSegmentButton	Control which draws a segmented button
Segment
CSliderBase
Impl
CSlider	Slider control
Impl
CVerticalSlider	Vertical slider control
CHorizontalSlider	Horizontal slider control
CSpecialDigit	Special display with custom numbers (0...9)
CSplashScreen
CAnimationSplashScreen	Splash screen which animates the opening and closing of the splash bitmap
StringListControlDrawer	A specialized list control drawer to draw strings
Impl
CSwitchBase
CVerticalSwitch	Vertical switch control
CHorizontalSwitch	Horizontal switch control
CRockerSwitch	Switch control with 3 sub bitmaps
CTextEdit	Text edit control
CTextLabel	Text label
CMultiLineTextLabel	Multi line text label
CVuMeter
CXYPad
ICommandMenuItemTarget	Command menu item target
CommandMenuItemTargetAdapter
IControlListener
IOptionMenuListener	Option menu listener
OptionMenuListenerAdapter
ITextEditListener	Listener for a text edit
TextEditListenerAdapter
ITextLabelListener	Listener for a text label
TextLabelListenerAdapter
COpenGLView	Subview which uses OpenGL for drawing
CPoint	Point structure
CRect	Rect structure
CResourceDescription	Describes a resource by name or by ID
CAutoLayoutContainerView	TODO: Doc
CRowColumnView	View container which layouts its subview as rows or columns
CScrollView	Scrollable container view with scrollbars
CShadowViewContainer	View container which draws a shadow for it's subviews
CSplitView	Split container view with separators between its child views
ISplitViewController	Split View Controller
ISplitViewSeparatorDrawer	TODO: Doc
UTF8CodePointIterator
UTF8String	Holds an UTF8 encoded string and a platform representation of it
TrimOptions
UTF8StringView	View on a null terminated UTF-8 String
UTF8CharacterIterator
CTabView	Tab view
CTooltipSupport	Generic Tooltip Support class
CView	Base Class of all view objects
Impl
CDragContainerHelper	Helper class to port old code which used CDragContainer
CViewContainerDropTarget
GetViewOptions
CViewContainer	Container Class of CView objects
Impl
Iterator
CVSTGUITimer	A timer class, which posts timer messages to CBaseObjects or calls a lambda function (c++11 only)
DispatchList
ListenerProvider
DragDescription	Drag description
IDraggingSession	Dragging session interface
DragEventData	Drag event data
IDropTarget	Drop target interface
IDragCallback	Drag callback interface
DragCallbackAdapter	Drag callback interface adapter
DragCallbackFunctions	Drag callback interface adapter which calls std::functions
DropTargetAdapter	Drop target interface adapter
DragStartMouseObserver	Helper object to be used to decide if a mouse move is far enough to start a drag operation
EventConsumeState	EventConsumeState
Event	Event
Modifiers	Modifiers
ModifierEvent	ModifierEvent
MousePositionEvent	MousePositionEvent
MouseEventButtonState	MouseEventButtonState
MouseEvent	MouseEvent
MouseEnterEvent	MouseEnterEvent
MouseExitEvent	MouseExitEvent
MouseDownUpMoveEvent	MouseDownUpMoveEvent
MouseDownEvent	MouseDownEvent
MouseUpEvent	MouseUpEvent
MouseMoveEvent	MouseMoveEvent
MouseCancelEvent	MouseCancelEvent
MouseWheelEvent	MouseWheelEvent
GestureEvent	GestureEvent
ZoomGestureEvent	ZoomGestureEvent
KeyboardEvent	KeyboardEvent
FinalAction
GenericStringListDataBrowserSourceSelectionChanged
GenericStringListDataBrowserSource	Generic string list data browser source
IDataBrowserDelegate	DataBrowser Interface
DataBrowserDelegateAdapter
IDataPackage	Interface for drag&drop and clipboard data
DataPackageIterator	IDataPackage iterator
Item
IFocusDrawing	Custom focus drawing interface
IScaleFactorChangedListener
IViewListener	View Listener Interface
IViewEventListener	View Event Listener Interface
IViewContainerListener	ViewContainer Listener Interface
ViewListenerAdapter	View Listener Interface Adapter
ViewEventListenerAdapter	View Event Listener Interface Adapter
ViewContainerListenerAdapter	ViewContainer Listener Interface Adapter
MallocAllocator
Buffer
Optional	Simplified optional
IReference
ReferenceCounted
CBaseObject	Base Object with reference counter
SharedPointer
CBaseObjectGuard
OwningPointer	An owning pointer
BitScopeToggleT
Base64Codec
Result
ZLibInputStream
ZLibOutputStream
ZLibInputContentProvider
CompressedUIDescription
OutputStream	ByteOrder aware output stream interface
InputStream	ByteOrder aware input stream interface
SeekableStream	Seekable stream interface
CMemoryStream	Memory input and output stream
CFileStream	File input and output stream
CResourceInputStream	Resource input stream
BufferedOutputStream
StdOutStream
DelegationController
IContentProvider
IController	Extension to IControlListener used by UIDescription
IContextMenuController	Extension to IController The VST3Editor checks all controllers of the views under the mouse on a right click if they have this interface implemented and calls the appendContextMenuItems before showing the context menu to the user
IContextMenuController2
IUIDescription
FocusDrawingSettings
IViewCreator	View creator interface
ViewCreatorAdapter	View creator interface adapter
IViewFactory
UIAttributes
MemoryContentProvider
InputStreamContentProvider
UIDescription	XML description parser and view creator
Impl
IBitmapCreator
IBitmapCreator2
UIDescriptionListener
UIDescriptionListenerAdapter
UIDescriptionListenerOff
ViewCreatorRegistry
UIViewFactory	Default view factory
UIViewSwitchContainer
IViewSwitchController
UIDescriptionViewSwitchController
AEffGUIEditor
ERect
ParameterChangeListener
IVST3EditorDelegate	Delegate interface for a VST3Editor
VST3EditorDelegate	Default adapter implementation for IVST3EditorDelegate
VST3Editor	VST3 Editor with automatic parameter binding
GroupController
PadController
Interface
PluginGUIEditor
VstKeyCode