only take into account visible children in DoLayout()

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39031 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/toplvcmn.cpp

@@ -338,7 +338,7 @@ void wxTopLevelWindowBase::DoLayout()
         }
 
         // do we have any children at all?
-        if ( child )
+        if ( child && child->IsShown() )
         {
             // exactly one child - set it's size to fill the whole frame
             int clientW, clientH;