This class implements IUIRenderer (see comments of IUIRenderer).

When creating the UIRenderer a UI theme (see Theme) must be specified. The renderer will use the attributes and styles of the theme to render the controls.

Thread-Safety: This class is not thread-safe. Render(UIControl, UIRenderContext) must not be called simultaneously in concurrent threads.

Render Callbacks: This class has a dictionary RenderCallbacks which defines the methods used for rendering. When Render(UIControl, UIRenderContext) is called, the style of the control is determined and the render callback for the style is used to render the control. If a render method is not given for a given style, the parent styles are used (a ThemeStyle can inherit from another style, see Inherits). See also RenderCallbacks.