use :: when referring to wxDefaultSize or wxDefaultPosition

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@60266 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/combobox.h

@@ -96,9 +96,10 @@ public:
             string must be one of the valid choices if it is not empty.
         @param pos
             Window position.
+            If ::wxDefaultPosition is specified then a default position is chosen.
         @param size
-            Window size. If wxDefaultSize is specified then the window is sized
-            appropriately.
+            Window size. 
+            If ::wxDefaultSize is specified then the window is sized appropriately.
         @param n
             Number of strings with which to initialise the control.
         @param choices