diff --git a/include/wx/defs.h b/include/wx/defs.h
index bbb1b4a9e9..61c5ca2d05 100644
--- a/include/wx/defs.h
+++ b/include/wx/defs.h
@@ -935,8 +935,16 @@ enum wxBorder
 // Windows, it won't normally get the dialog navigation key events)
 #define wxWANTS_CHARS           0x00040000
 
-// Make window retained (mostly Motif, I think) -- obsolete (VZ)?
+/*  Make window retained (Motif only, see src/generic/scrolwing.cpp)
+ *  This is non-zero only under wxMotif, to avoid a clash with wxPOPUP_WINDOW
+ *  on other platforms
+ */
+
+#ifdef __WXMOTIF__
 #define wxRETAINED              0x00020000
+#else
+#define wxRETAINED              0x00000000
+#endif
 #define wxBACKINGSTORE          wxRETAINED
 
 // set this flag to create a special popup window: it will be always shown on