Weird (erroneous) behaviour of Menu Start selection page

We've come across weird behaviour when selecting folder for Menu Start page.
Namely, when clicking in the folders list, but not on any item, then 6-digit number is prepended to the path and the base dir is repeated with every click.
If list is too long, scroll down and click right under the last item. It's important not to select any item before trying this out.

I'm not sure if I explained it well enough, thus below I provide video produced by one of our testers showing exactly how to reproduce this error.
It says I can upload only 256 kb attachment, and the video packed has 5mb, so I upload it to my site:
http://sinnerinc.net/nsis-bug/WeirdNsis.zip

Also, since I was uncertain whether that's NSIS fault or just some buggy script of mine, I downloaded third-party app (bittorrent.com, for that matter) and it can
be reproduced with their installer as well - screenshot in attachment.

I tried it on NSIS 2.44 and 2.45, on Polish and English WinXP Professional.