Invalidate best size after string change in wxChoice.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@46233 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/choice.cpp

@@ -374,6 +374,8 @@ void wxChoice::SetString(unsigned int n, const wxString& str)
 
             gtk_label_set_text( label, wxGTK_CONV( str ) );
             
+            InvalidateBestSize();
+
             return;
         }
         child = child->next;