Add more comments about ref counting and cow to

brush, pen, font and region.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43567 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/pen.tex

@@ -59,10 +59,11 @@ get a pointer to a pen by using the global list of pens {\bf
 wxThePenList}, and calling the member function {\bf FindOrCreatePen}.
 See the entry for \helpref{wxPenList}{wxpenlist}.
 
-wxPen uses a reference counting system, so assignments between pens are very
-cheap. You can therefore use actual wxPen objects instead of pointers without
-efficiency problems. Once one wxPen object changes its data it will create its
-own pen data internally so that other pens, which previously shared the
+This class uses \helpref{reference counting and copy-on-write}{trefcount}
+internally so that assignments between two instances of this class are very
+cheap. You can therefore use actual objects instead of pointers without
+efficiency problems. If an instance of this class is changed it will create
+its own data internally so that other instances, which previously shared the
 data using the reference counting, are not affected.
 
 %TODO: an overview for wxPen.