Document that wxPoint(wxRealPoint) ctor truncates, not rounds.

Also give an example showing how to do rounding instead.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73816 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/gdicmn.h

@@ -605,6 +605,16 @@ public:
     /**
         Converts the given wxRealPoint (with floating point coordinates) to a
         wxPoint instance.
+
+        Notice that this truncates the floating point values of @a pt
+        components, if you want to round them instead you need to do it
+        manually, e.g.
+        @code
+            #include <wx/math.h>    // for wxRound()
+
+            wxRealPoint rp = ...;
+            wxPoint p(wxRound(rp.x), wxRound(rp.y));
+        @endcode
     */
     wxPoint(const wxRealPoint& pt);