fix initial best size of (check) list boxes under MSW

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57367 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/listbox.cpp

@@ -177,7 +177,8 @@ bool wxListBox::Create(wxWindow *parent,
         Append(choices[i]);
     }
 
-    // now we can compute our best size correctly, so do it if necessary
+    // now we can compute our best size correctly, so do it again
+    InvalidateBestSize();
     SetInitialSize(size);
 
     return true;