Wireshark-dev: [Wireshark-dev] Warning users on XP *before* uninstalling the old version?
From: Evan Huus <eapache@xxxxxxxxx>
Date: Sat, 9 Aug 2014 21:55:01 -0400
Per this comment, seems like it would be a good idea:
https://blog.wireshark.org/2014/07/wireshark-1-12-officially-released/comment-page-1/#comment-3385

Don't know much about the Windows installer though, this may not be possible?