A wxClientDC must be constructed if an application wishes to paint on the client area of a window from outside an OnPaint event. This should normally be constructed as a temporary stack object; don't store a wxClientDC object.
To draw on a window from within OnPaint, construct a wxPaintDC object.
To draw on the whole window including decorations, construct a wxWindowDC object (Windows only).
wxDC, wxMemoryDC, wxPaintDC, wxWindowDC, wxScreenDC
Constructor. Pass a pointer to the window on which you wish to paint.