oWin:BeginPaint( ) -> NIL

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 DESCRIPTION:

  The BeginPaint function prepares the specified window for painting.
  It creates a Device Context and fills a PAINTSTRUCT structure
  with information about the painting.

  The hDC is stored in ::hDC, the Paintstructure in ::cPS

  This method is automatically called from fivewin / windows after sizing,
  moving, creating, scrolling, or any other operation that affects the
  client area of the window. Each call to ::BeginPaint() must have a
  corresponding call to ::EndPaint(). You can monitor this with the
  counter-iVar ::nPaintCount.

  Think of ::BeginPaint() as of some kind of advanced DispBegin() ..