added wxFlexGridSizer::Add{Row,Col}Growable() (#2603)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54607 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/sizer.h

@@ -785,6 +785,8 @@ public:
     void AddGrowableCol( size_t idx, int proportion = 0 );
     void RemoveGrowableCol( size_t idx );
 
+    bool IsRowGrowable( size_t idx );
+    bool IsColGrowable( size_t idx );
 
     // the sizer cells may grow in both directions, not grow at all or only
     // grow in one direction but not the other