1. minor headers rearrangement: wxprec.h doesn't include setup.h directly

any more, btu defs.h does - and not in the very beginning, but a bit
   later
2. some unused and uncompileable OS2 thing removed from string.cpp


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@3242 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/window.tex

@@ -137,15 +137,15 @@ Centres the window.
 \wxheading{Parameters}
 
 \docparam{direction}{Specifies the direction for the centering. May be {\tt wxHORIZONTAL}, {\tt wxVERTICAL}\rtfsp
-or {\tt wxBOTH}. It may also include {\tt wxCENTER\_FRAME} flag if you want to center the window
-on its parent and not on the screen (actually, this flag is added automatically for all controls
-because it makes no sense to center them on the screen)}
+or {\tt wxBOTH}. It may also include {\tt wxCENTRE\_ON\_SCREEN} flag if you
+want to center the window on the entire screen and not on its parent window. 
+
+The flag {\tt wxCENTRE\_FRAME} is obsolete and should not be used any longer.
 
 \wxheading{Remarks}
 
-The actual behaviour depends on the derived window. For a frame or dialog box,
-centring is relative to the whole display. For a panel item, centring is
-relative to the panel.
+If the window is a top level one (i.e. doesn't have a parent), it will be
+centered relative to the screen anyhow.
 
 \wxheading{See also}