-Returns the default size for the given art {\it client} by either using the topmost
-wxArtProvider or if {\it platform_default} is \true then return a suitable default size for
-{\it client} depending on the current platform.
+Returns a suitable size hint for the given {\it wxArtClient}. If
+{\it platform\_default} is \true, return a size based on the current platform,
+otherwise return the size from the topmost wxArtProvider. {\it wxDefaultSize} may be
+returned if the client doesn't have a specified size, like wxART\_OTHER for example.