colors with alpha are supported, so instances {\tt wxPen} or {\tt wxBrush} that are built from {\tt wxColour} use
the color's alpha values when stroking or filling.
+Note that beginning with wxWidgets 2.9.0 the entire wxDC code has been
+reorganized. All platform dependent code (actual all drawing code) has
+been moved into backend classes which derive from a common wxDCImpl
+class. The user-visible classes such as wxClientDC and wxPaintDC
+merely forward all calls to the backend implementation.
+
\wxheading{Derived from}
\helpref{wxObject}{wxobject}