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

aggregator
AggregatorCollection
ArrowItem
ArtificialHorizon
ArtificialHorizonPlugin
BoundarySlider
Compass
CompassPlugin
ContextMenuGraphicsWidget
DrawItem
EllipseItem
FillItem
GraphicsPointsItem
ImageView	Image viewer with optional text and geometry overlay functionality
ImageViewOld
ImageViewOldGL
ImageViewOldPlugin
ImageViewPlugin
IndexSlider
KeyEvent
LineItem
MultiViewPlugin
MultiViewWidget
MultiWidget
MultiWidgetPlugin
OrientationPlugin
OrientationView
PaintWidget
Plot2d
Plot2dPlugin
PointItem
PolygonItem
PolylineItem
ProgressIndicator	Lets an application display a progress indicator to show that a lengthy task is under way
ProgressIndicatorPlugin
QCPAbstractLegendItem	The abstract base class for all items in a QCPLegend
QCPAbstractPlottable	The abstract base class for all data representing objects in a plot
QCPAxis	Manages a single axis inside a QCustomPlot
QCPBarData	A class holding the data of one single data point (one bar) for QCPBars
QCPBars	A plottable representing a bar chart in a plot
QCPCurve	A plottable representing a parametric curve in a plot
QCPCurveData	A class holding the data of one single data point for QCPCurve
QCPData	A class holding the data of one single data point for QCPGraph
QCPGraph	A plottable representing a graph in a plot
QCPLegend	Manages a legend inside a QCustomPlot
QCPPlottableLegendItem	A legend item representing a plottable with an icon and the plottable name
QCPRange	Represents the range an axis is encompassing
QCPStatisticalBox	A plottable representing a single statistical box in a plot
QCustomPlot	The central class which is also the QWidget which displays the plot and interacts with the user
QWaterfallDisplay
RangeView
RangeViewGL
RangeViewPlugin
RectangleItem
RockSlider
RockSliderPlugin
RockWidgetCollection
SlideBarItem
Slider
SonarDisplay
SonarDisplayPlugin
SonarPlot
SonarView
SonarViewGL
SonarViewPlugin
SonarWidget
SonarWidgetPlugin
StreamAlignerDelegate
StreamAlignerModel
StreamAlignerWidget
StreamAlignerWidgetPlugin
StreamRepresentation
TaskRepresentation
TestWidget
TextItem
Timeline
TimelinePlugin
Vectorfield3D	Widget to display vector (flux density) fields in Vizkit based on VTK
Vectorfield3DPlugin
VirtualJoystick
VirtualJoystickPlugin
WaterfallDisplayPlugin
WidgetButton
WidgetButtonPlugin
WidgetTester