wxSnip * MergeWith (wxSnip *pred)
Merges this snip with the given snip. This method will only be invoked if both snips are from the same class and both have the wxSNIP_CAN_APPEND flag. Override this method in your own snip class if its possible for two of your snips to be merged.
If the merge fails, NULL will returned. Otherwise, the return value is the merged snip. Both old snips are considered destroyed if the merge succeeds.